Michel Roux Jr’s Lyonnais potato cake is made with slowly cooked onions and potatoes baked with crème fraîche and a sprinkling of nutmeg. The side dish recipe can be made ahead of serving.
Serves 6-8
4 large baking potatoes
2 large onions, sliced
1 tbsp vegetable oil
1 tbsp butter for greasing
1 free-range egg, beaten
2 tbsp full fat crème fraîche
Good grating nutmeg
Fresh thyme to serve
Heat the oven to 400F/200°C/fan180°C/gas 6.
Bake the potatoes in their skins for 1½ hours or until soft, leave to cool, then spoon out the flesh into a bowl, Mash out any lumps with a potato masher. (see tips). Turn the oven down to 350F/180°C/fan160°C/gas 4.
Meanwhile, put the sliced onions and the oil in a large saucepan over a low heat and fry for 45 minutes, stirring often, until golden.
Grease a non-stick, loose-bottomed round sandwich tin (about 8″/20cm across) with the butter and line with baking paper. Gently mix the beaten egg and crème fraîche into the potato, then gently mix in the onions and season with salt, pepper and a good grating of nutmeg.
Tip the mix into the tin and bake for 45 minutes or until golden.Remove and leave to cool for 5 minutes before turning out. (You may need to run a blunt knife around the edge to release it.) Top with fresh thyme leaves to serve.
Tips
Handle the potatoes with a tea towel if they’re not completely cool. If they’re not entirely soft and still have lumps, mash briefly with a masher.
Cook the potato cake up to 3 days ahead, then keep covered and chilled. Reheat in a 350F/180°C/fan160°C/gas 4 oven for 30-40 minutes to serve.