Half-fill a large pan with water. Add a pinch of salt. Cover and put on a high heat to come to the boil. Scrub and peel the potatoes (see our tips on how to make the most of your veg peelings). Chop the potatoes into rough 3-4cm chunks. When the water is boiling, add the potatoes. Turn the heat down to a simmer, and cook the spuds for 5-6 mins.

Heat your oven to 200°C/Fan 180°C/ Gas 6. Add 1 tbsp olive oil to a large roasting tin, or 2 medium tins. Put them in the oven for 10 mins to heat the oil.

Drain the potatoes, then tip them back into the pan. Put the lid on the pan and shake it gently a few time to rough the edges of the potatoes (be careful not to break the potatoes up too much).

Take the roasting tin out of the oven. Add 50g of the butter (save the rest of the butter for your other recipes) and swirl to melt it. Add the potatoes. Season with a pinch of salt and pepper. Turn the spuds a few times to coat in the hot oil and butter. Slid into the oven and roast for 45 mins, till golden brown. If you’re using 2 tins, swap them over halfway through cooking.

While the potatoes roast, finely chop the rosemary leaves. When the spuds are ready, tip them into a serving bowl and scatter over the chopped rosemary leaves to serve.