Steps
- Melt 25g of butter in a pan over medium-low heat. Soften 3 finely sliced onions for 10-15 minutes, then cool.
- Preheat the oven to 375°F / 190°C with a baking sheet inside. Beat 2 eggs; stir in the onions and 400g of grated extra-sharp Cheddar. Season with salt and pepper.
- Use half of 640g of ready-rolled shortcrust pastry to line a 9in / 23cm pie dish. Add the filling. Beat 1 egg and brush the pastry rim.
- Cover with the remaining pastry; trim, seal, crimp, and cut a steam vent. Brush with egg. Bake on the hot sheet for 40-50 minutes, until golden; cool slightly before slicing.