The hairy bikers butter and potato pie recipe on Saturday Kitchen

Si and Dave served up a butter and potato pie with mushroom gravy on Saturday Kitchen.

The ingredients for the filling: 900g medium potatoes (preferably Maris Piper), 75g fridge-cold butter, cut into 1cm cubes, 1 large onion, sliced into thin rings, flaked sea salt and freshly ground black pepper.

For the pastry: 350g plain flour, plus extra for rolling, 175g butter, 50g extra mature cheddar cheese, finely grated, 1 large free-range egg, beaten with 1 tbsp cold water
beaten egg, to glaze.

For the mushroom gravy: 500ml just-boiled water, 2 tsp vegetable bouillon powder (or ½ vegetable stock cube), 10g dried mushrooms, either mixed or porcini, 1 tbsp sunflower oil, 15g butter, 150g small chestnut mushrooms, wiped and finely sliced, 1 tbsp plain flour, 2 tbsp finely snipped fresh chives (optional), flaked sea salt and freshly ground black pepper.

For the wilted spinach with nutmeg: large bag young spinach leaves, 25g butter, freshly grated nutmeg, to taste, salt and freshly ground black pepper.