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Thyme & Onion Butter
Thyme and onion butter is one of those ridiculously useful things I like having tucked away in the fridge or freezer. Sweet onion, fragrant thyme and parsley are folded through butter with a little oil to keep it wonderfully spreadable, ready for toast, vegetables, potatoes, pasta, chicken, or a very nostalgic batch of herb and onion bread.
Homemade Spreadable Thyme & Onion Compound Butter
Thyme and onion compound butter is one of those little things that makes everything taste better. I soften good butter and mix it with caramelised onion, fresh thyme, and a pinch of salt – then roll it up and keep it in the fridge. It melts beautifully over grilled meats, roasted veg, or even a slice of warm sourdough. It’s simple to make, easy to store, and adds instant flavour whenever a dish needs that extra something. Proper kitchen magic in a log.
Ingredients
- 250g salted butter, room temperature and roughly chopped
- 1 tbsp olive oil or rapeseed oil
- 100g onion, finely diced
- 10g fresh thyme leaves
- 10g fresh parsley
- Large pinch of Maldon sea salt flakes
Instructions
- Heat the oil in a small frying pan over medium-low heat. Add the onion and cook gently for 8-10 minutes, or until completely soft, sweet, and just starting to turn golden. Set aside to cool completely.
- Add the butter, cooled onion, thyme, parsley, and salt to a food processor. Blitz until well combined and the herbs are finely incorporated.
- Taste and adjust the seasoning if needed.
- Spoon the butter onto a sheet of cling film or baking paper and roll into a log shape. Twist the ends tightly to seal.
- Refrigerate for at least 2 hours until firm, or freeze until needed.
Notes
- Compound butter is one of those things that sounds fancy but takes almost no effort and makes everything it touches taste significantly better. A slice melting over a hot steak is one of life's great pleasures.
- Cooking the onion low and slow until completely soft is important. Raw onion in compound butter has too sharp a bite and an unpleasant texture. You want it sweet, soft, and golden.
- Let the onion cool completely before adding it to the butter. Warm onion will melt the butter and give you a greasy, broken mixture rather than a smooth, spreadable compound butter.
- Room temperature butter is essential. Cold butter won't blend smoothly with the other ingredients and you'll end up with lumpy, uneven results.
- Rapeseed oil has a neutral flavour and works beautifully for cooking the onions. Olive oil adds a subtle fruitiness. Either works well.
- Fresh thyme and parsley give a much brighter, more vibrant flavour than dried herbs. Don't substitute with dried here.
- Roll the butter log as tightly as you can in the cling film to get a neat, uniform shape. This makes slicing clean rounds easy when you're ready to use it.
- I use this food processor for compound butters. It blends everything evenly without overworking the butter.
- This butter keeps in the fridge for up to 2 weeks, tightly wrapped. The flavour actually improves after a day or two as everything melds together.
- You can freeze this butter for up to 3 months. Slice the log into rounds before freezing so you can pull out individual portions as needed without defrosting the whole thing.
What I Cook With
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Nutrition Information:
Yield:
25Serving Size:
1Amount Per Serving: Calories: 89Total Fat: 10gSaturated Fat: 5gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 22mgSodium: 70mgCarbohydrates: 1gFiber: 0gSugar: 0gProtein: 0g
Please note, this nutrition information is to be used as a guide only. Nutrition information isn’t always accurate.
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Serve this with
- Spread over warm bread and serve with my Spaghetti Bolognese with Red Wine as a change from garlic bread. The sweet onion and fragrant thyme are brilliant with the rich, slow-cooked tomato sauce.
- Melt a generous slice over grilled steak or lamb cutlets just before serving. The butter melts into the meat juices, while the thyme and onion add loads of flavour without needing another sauce.
- Toss through my Rosemary and Garlic Roast Potatoes just before serving for an extra buttery finish. The sweet onion and thyme add another savoury layer and work especially well as part of a Sunday roast.
A Family Favourite
One of the very first things I ever got to “cook” as a kid was garlic bread. Not the frozen baguette wrapped in foil, but proper homemade garlic bread where you mix the butter and garlic yourself and slather it over thick slices of bread before baking. Tuesday night was always Spaghetti Bolognese night in our house, and garlic bread was a non-negotiable part of the meal. But every now and then Mum would swap it out for herb and onion bread, and honestly, I think I loved that even more.
It was sweet from the onion, fragrant with whatever herbs Mum had around, and somehow felt a little bit special despite being incredibly simple. To this day, that flavour combination takes me straight back to those warm, carb-heavy Tuesday dinners. So naturally, now that I’m an adult with a completely reasonable collection of homemade compound butters in the freezer, thyme and onion butter has become one of the versions I make most often. Some childhood habits really do just evolve rather than disappear.
I use this on everything. Hot toast, roast vegetables, pasta, chicken, potatoes, or spread thickly over bread before it goes into the oven to become my grown-up version of Mum’s herb and onion bread. The little addition of olive oil, or another neutral oil, keeps it softer and more spreadable straight from the fridge too, which means no hacking away at a rock-hard block of butter with a knife. I can just scoop out what I need and get on with dinner. It tastes nostalgic enough to remind me of home, but useful enough that I genuinely keep finding new reasons to have a batch waiting in the fridge.
Freezer Staples and Fancy Twists
I love compound butter because it’s one of those ridiculously easy things that makes an ordinary dinner feel as though you’ve put in far more effort than you actually have. Most of the time I make a batch because I’ve got fresh herbs that need using or half an onion sitting in the fridge with no obvious future. A few minutes later, those odds and ends have become something I can use for weeks rather than another forgotten ingredient quietly dying behind the milk.
Usually I roll the finished butter into a log, wrap it well, and freeze it. If I’m feeling unusually organised, I’ll slice it into discs first so I can grab exactly what I need. Let’s not pretend that happens every time, though. More often I freeze the entire thing and deal with portioning it later. However it gets there, having flavoured butter tucked away in the freezer is incredibly useful when dinner needs a little help and I don’t particularly feel like inventing anything complicated.
This thyme and onion butter has ended up on roast chicken, stirred through rice, melted over vegetables, and folded into scrambled eggs. Once I put a generous piece onto a baked potato, covered the whole thing with grated cheese, and briefly wondered why I ever bother making elaborate meals. That’s the beauty of it. Pull some sausages from the freezer, boil or roast a few potatoes, add a little of this butter and suddenly dinner tastes considered. It works hard so I don’t have to, which is exactly what I want from a fridge staple. Not every meal needs a grand plan. Sometimes butter with herbs and onion is doing more than enough.
The Photography Struggle
I’ll also admit that I’m absolutely shocking at remembering to photograph compound butters. I’ll make one, taste it, decide it’s brilliant, use it on three different meals, and then suddenly realise I’ve got barely any left and not a single useful photo. My brain seems to completely forget that I run a food blog the moment something this simple is ready to eat. I probably have a dozen little butter combinations I’ve made over the years that have never appeared here for exactly that reason.
I’m always slightly in awe of food bloggers who manage to photograph every stage of a recipe while keeping their kitchen looking spotless. That has never been my reality. I’m usually elbow-deep in whatever I’m making, herbs stuck to my hands, dishes accumulating beside the sink, and halfway through tasting something before I remember it was meant to be photographed first. The actual camera is my phone, so you’d think this would make matters easier, but apparently having it within reach still doesn’t guarantee I’ll remember to use it.
So if a compound butter recipe does make its way onto this blog, you can safely assume it has already been made, eaten, remade, and worked its way into my normal cooking long before I sit down to share it. I’m not making these because I need another recipe to post. I make them because they’re useful, delicious, and exactly the kind of tiny kitchen shortcut I genuinely rely on. Thyme and onion butter has earned its place here the old-fashioned way, by repeatedly disappearing from my fridge and freezer. At least this time I remembered the photos before I spread the final spoonful onto toast.
Frequently asked questions
Why do I need to cook the onion before adding it to the butter? Raw onion in compound butter has too sharp a bite and an unpleasant raw texture that doesn’t mellow out in the fridge. Cooking it low and slow for eight to ten minutes until completely soft, sweet, and just starting to turn golden transforms it entirely. You want the sweetness of a properly cooked onion rather than the sharpness of a raw one running through every slice of butter.
Why does the butter and onion need to be at room temperature before blending? Two different reasons. Room temperature butter blends smoothly and evenly with the other ingredients rather than staying in lumps. And the onion needs to be completely cool before it goes in because warm onion will melt the soft butter and give you a greasy, broken mixture rather than something smooth and spreadable. Both need to be at the same temperature before anything goes into the food processor.
How do I get a neat log shape? Spoon the butter onto a sheet of cling film or baking paper, shape it roughly into a log with a spatula, then roll it up tightly and twist both ends in opposite directions like a Christmas cracker. The tighter you roll it the more uniform the shape, which makes slicing clean rounds much easier when you’re ready to use it.
Ingredient breakdown
Salted butter
Room temperature and roughly chopped before going into the food processor, which is important for two reasons. Room temperature butter blends smoothly and evenly with the herbs and onion, and roughly chopping it means the processor doesn’t have to work hard to break it down before everything comes together. Salted butter rather than unsalted because the salt is already incorporated and distributes evenly through the finished compound butter without needing to be mixed in separately.
Olive oil or rapeseed oil
The fat the onion cooks in, and the choice between the two is a flavour preference rather than a functional one. Rapeseed oil is neutral and lets the onion and thyme flavour come through without any additional character. Olive oil adds a subtle fruitiness that suits the herbs well. Either works beautifully.
Onion
Cooked low and slow for eight to ten minutes until completely soft, sweet, and just starting to turn golden before it goes anywhere near the butter. This is the step that makes the compound butter worth making. A properly cooked onion adds a deep, sweet savouriness that raw onion never could, and the texture after cooking is smooth enough to blend seamlessly into the butter. Let it cool completely before it goes into the food processor or it will melt the soft butter and break the whole mixture.
Fresh thyme leaves
One of the two herbs that define the flavour profile of this compound butter. Fresh thyme has a slightly floral, earthy character that blends beautifully with the sweet cooked onion and works particularly well melting over grilled meat. Fresh only. Dried thyme has a dusty, muted flavour that won’t give you the same vibrant result.
Fresh parsley
The second herb, adding a clean, slightly peppery freshness that lifts the richness of the butter and balances the earthiness of the thyme. Flat-leaf parsley has a more assertive flavour than curly and is the better choice here. Fresh only, for the same reasons as the thyme.
Maldon sea salt flakes
A large pinch goes in with everything else before blending, seasoning the compound butter evenly throughout. Taste after blending and adjust if needed. The salted butter is already contributing saltiness so go carefully before adding more.
