Welsh onion cake – new recipe

Welsh onion cake

This Welsh Onion Cake is a humble dish which takes less than ten minutes to prepare, and can sit in your oven on a Sunday while your lunch is roasting. And for those of you Sunday lunch purists who insist on roast potatoes with your roast, I promise you that you won’t be disappointed with this alternative potato dish.

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Welsh potato cake

Welsh heritage

Now, my Welsh boyfriend has never heard of this Welsh onion cake, and I can’t find anything online to clarify the origins of this dish, but there are a lot of references online to ‘Welsh onion cake’ so let’s believe it really is Welsh! And it doesn’t really matter – it’s totally delicious so just make it and call it whatever you like. I mean, if we were being totally literal, we would be calling this potato and onion cake, right?! With a bit of cheese if you have some.

Plenty of potatoes in this ‘onion cake’

It’s called an onion cake, but in fact this Welsh onion cake is potatoes layered with onions and cheese, and baked in the oven. Make sure you liberally butter your dish, and you’ll end up with gorgeously crispy potatoes at the edges and top, and soft potatoes in the middle. My favourite bits are the crispy ones, so I always steal most of those bits when I am dishing up!

Welsh potato cake ingredients

So simple to make

Honestly this Welsh onion cake is unbelievably easy to make: butter a dish, layer with sliced potatoes, sliced onions and grated cheese. Top with some knobs of butter. Bake. I don’t even peel my potatoes! Although – sorry – you do have to peel the onions …

Serving suggestions for this delicious onion and potato side dish

I like this Welsh onion cake instead of roast potatoes for my Sunday lunch when I have a gravy-free roast (eg gammon). It’s really, really nice served with gammon or baked ham and some green veggies. It’s also very nice to eat cold as leftovers the following day!

Welsh potato cake and gammon

The best tip I can share: butter

Now I am no James Martin, obsessing with butter and adding blocks of it to every dish I make, but in this case, you do need a decent amount of butter in my Welsh onion cake. Generously grease your dish with butter and you won’t be disappointed – not only will the onions and potatoes not stick, but you will end up with those wonderful crispy pieces of potato and onion which are, in my view, the best bits!


Of course this is a very easy dish to make vegan: simply replace the butter with your preferred dairy free spread, and either omit the cheese entirely or use your favourite plant-based version.

Welsh potato cake

Welsh onion cake

Tracy Knatt
This Welsh onion cake is simple to make and layered with buttery, crispy, sliced potatoes and onions, with some grated cheese.
Course Side Dish
Cuisine British, Welsh
Servings 6 people


  • A casserole dish or baking tray with sides


  • 100 g butter
  • 4 large potatoes
  • 2 onions
  • 100 g cheese


  • First pre-heat your oven to around 180 degrees fan / Gas Mark 6. BUT, if you are already using your oven to roast your Sunday lunch, just maintain that temperature - this Welsh onion cake is hardy and can cope with whatever temperature you throw at it!
  • Firstly slice all of your potatoes as thinly as you can (but don't worry yourself too much if they are a bit thick - I don't use a mandolin or anything like that). I don't peel my potatoes either - it's up to you if you want to.
  • Slice your onions thinly and grate your cheese.
  • Generously butter your dish.
  • Layer your buttered dish with a layer of potatoes (I use up the halves and scraps of potato for this bottom layer, which won't really be seen).
    Welsh potato cake inside layer
  • Add a layer of sliced onions and some grated cheese, then season with salt and pepper.
  • Repeat with more layers of potato, onion, cheese and seasoning (I normally get 2 layers of each plus a final one of potatoes).
  • Try to save the nicest looking whole slices of potato to top the dish, as this will be the layer you see when you take the dish to the table (if you care about that kind of thing!).
  • Top the Welsh onion cake with a few knobs of butter and cover loosely with tin foil.
    Welsh potato cake top
  • Bake for one hour covered, and then for a further 30 minutes uncovered, leaving you with soft potatoes and onions underneath a buttery, crispy layer of potatoes (my favourite bit).


Serve immediately, although this is pretty epic served the following day, so enjoy your leftovers.
Keyword cheese, easy recipe, onions, potatoes

Interested in some other Welsh classic dishes? Check these out:

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