Traditional Welsh Onion Cake (Teisen Nionod)

Welsh onion cake on a plate next to a side salad

Traditional Welsh Onion Cake (Teisen Nionod)

Golden and crisp on top with buttery, tender layers beneath, Welsh onion cake - known in Welsh as teisen nionod or teisen winwns, depending on where you are - is a traditional savoury bake that has long been associated with Welsh home cooking. Despite its name, it isn't a cake in the sweet sense, but a hearty dish made from potatoes and onions, generously buttered before being baked until beautifully golden. 

Traditionally served alongside roast meats or enjoyed as a meal in its own right alongside a crisp side salad, it relies on good-quality ingredients rather than complicated techniques. This version stays true to the classic while adding sweet leeks and mature Cheddar for extra richness, creating a comforting bake that's just as suitable for a family supper as it is for entertaining. 

Although its exact origins are uncertain, teisen nionod is thought to date back to the 19th century, when potatoes became a staple ingredient in Welsh kitchens.

Course Dinner, Lunch, Main Course, Side Dish

Cuisine British, UK, Welsh

Keyword budget, easy, savoury bake, Vegetarian, welsh onion

Prep Time 25

Cook Time 1 30

Resting Time 10

Total Time 2 5

Servings generous slices

Calories 502kcal

Author Kacie Morgan

Cost £1

Equipment

Ingredients

3 medium onions approx. 300g, peeled
700 g Red, Désirée or Maris Piper potatoes peeled
1 large leek approx. 150g washed, trimmed and halved lengthways
100 g unsalted butter melted, plus 1 tbsp melted butter for brushing
150g g mature Cheddar grated
2 tsp fresh thyme leaves
salt and pepper to season

Instructions

Preheat the oven to 220°C / 200°C fan/Gas Mark 6.
Slice the onions, potatoes and leeks into 2-3mm rounds using a mandoline or a sharp knife.
Grease a deep 23-24cm round pie dish or cake tin.
Toss the potato slices with most of the melted butter until lightly coated, reserving some for basting and pouring over the top.
Arrange a layer of potato slices over the base, and season lightly with salt and pepper. then top with some of the onions and leeks. Add another light seasoning, a scattering of Cheddar and a few thyme leaves. Repeat the layers until all the ingredients have been used, finishing with a layer of potatoes.
Press down gently on each layer as you build the onion cake to help create neat, compact layers.
Top with some of the onions...
... followed by a layer of leeks.
Add a scattering of Cheddar and a few thyme leaves.
Repeat the layers until all the ingredients have been used, finishing with a layer of potatoes. Season with salt and pepper.
Press down gently on each layer as you build the onion cake to help create neat, compact layers.
Brush the final potato layer with melted butter, and pour any remaining melted butter into the dish. Cover with foil, and bake for 1 hour.
Remove the foil and brush the surface with the remaining tablespoon of melted butter. Reduce the oven temperature to 200°C / 180°C fan/Gas Mark 6. Return to the oven for 30 minutes more, or until the potatoes are completely tender and the top is crisp and deeply golden.
Leave to rest for 10 minutes before garnishing with a few extra thyme leaves. Serve warm with a lightly dressed salad as a main meal, or with roast meats or sausages as a side dish.

Notes

Slicing the veg: You can use a sharp knife to slice the potatoes, leeks and onions, but a mandoline will produce the most even slice - just be sure to use the safety guard, and consider wearing cut-resistant gloves for added protection.
Potatoes: Désirée potatoes hold their shape well while becoming beautifully soft, although Maris Piper and Red potatoes also work well.
Cheese: Mature Cheddar adds a rich savoury flavour without overwhelming the potatoes and onions. For a more traditional Welsh twist, try replacing some or all of it with Caerphilly cheese. Alternatively, omit the cheese altogether for a lighter, more traditional approach.
Servings: This recipe produces four generous servings to be eaten as part of a main meal, or six smaller slices to enjoy alongside a main meal.
To reheat: To reheat the whole onion cake, cover it with foil and place it on a baking tray in an oven preheated to 170°C fan / 190°C / 375°F / Gas Mark 5 for 20-25 minutes, or until piping hot throughout. Remove the foil for the final 5 minutes to help restore the crisp, golden top. For individual slices, reheat in the same oven for 10-15 minutes, or in an air fryer at 180°C for 8-10 minutes, checking occasionally to prevent over-browning.
Storage: Allow the Welsh onion cake to cool completely, then cover and refrigerate for up to 3 days. It can also be frozen for up to 3 months. Defrost overnight in the fridge before reheating.

Nutrition