Homity Pie with Cheddar, Potatoes and Leeks

Make the pastry. In a large bowl, combine the plain flour, wholemeal or rye flour, salt and cayenne, if using. Rub in 125 g of the butter with your fingertips until the mixture looks like coarse breadcrumbs. Stir in the egg and 1 tbsp cold water with a table knife, then bring the dough together into a ball. Cover and chill for 30 minutes.

Roll out the chilled pastry on a lightly floured surface until large enough to line a 20 cm deep pie dish. Press it into the base and sides, trim the edges, then return the pastry case to the fridge while you prepare the filling.

Melt the remaining 25 g butter in a large saucepan over medium heat. Add the onions, leek, thyme, salt and pepper, then cook for 12-15 minutes, stirring often, until soft, sweet and lightly sticky.

Stir in the sliced potatoes, reduce the heat to low, cover and cook for 10-15 minutes, stirring occasionally, until the potatoes are tender and beginning to break down when pressed with a spoon. Add the double cream, stir for 1 minute, then remove from the heat and let the filling cool slightly.