Homity Pie with Potato, Cauliflower & Cheddar

Ingredients

• 250g plain flour, plus extra for dusting
• pinch of salt
• 1 tsp caraway seeds, lightly cracked in a mortar and pestle
• 150g butter
• 1 egg, beaten, plus extra for brushing
• 500g new potatoes, peeled and thinly sliced (about 1cm/1⁄2in thick)
• 30g butter or extra virgin olive oil
• 1 large onion, thinly sliced
• 1⁄2 smallish cauliflower, thinly sliced
• 150g Cheddar, coarsely grated or crumbled small
• 1⁄4 freshly grated whole nutmeg
• small bunch of chives, thinly sliced
• 250ml double cream
• Flaky sea salt and freshly ground black pepper