To make the filling, peel the potatoes and chop into quarters. Bring a pan of salted water to the boil, add the potatoes and simmer for 20 mins until soft. Drain and leave to cool. Meanwhile, fry the onions gently in the butter for 8 mins until soft and translucent. Set a couple of tablespoons aside to serve with the dumplings, if you like. Add the cottage cheese and onions to the potatoes, season with salt and pepper, then mix and mash everything thoroughly.

Mix the flour with 450ml tepid water, 10g salt and the oil, then knead thoroughly to make a smooth dough. Leave to rest for 15 mins. Split the dough into two and roll the first half thinly to 1-2mm on a lightly floured surface. Cut out the circles with a rim of a glass or an 8cm pastry cutter, then fill each one with 1 heaped tbsp of stuffing. Pinch the edges of the pierogi together with a little water, making sure they are firmly sealed. Any leftover stuffing can be frozen to make more pierogi or to enjoy as a mash to accompany stews or casseroles.

Bring about 2 litres of water to the boil in a large pan with a little salt added. When the water is bubbling, lower in the pierogi in batches. They should cook in 5-6 mins – you'll know they're ready when they rise to the surface. Scoop them out using a slotted spoon. Heat some butter in a frying pan and toss the pierogi in it until lightly browned. If you've set aside some fried onions, add those too and use these to dress the pierogi, if you like. Will keep frozen for up to three months. Leave to cool completely first. Reheat in boiling water.