Heat oven to 220C/200C fan/gas 7. Heat 1 tbsp of the oil in a large, lidded frying pan or flameproof casserole dish. Cook the aubergine, in two batches, over a high heat for 4-5 mins until golden, adding extra oil as you need to. Return all the aubergine to the pan with the garlic, tomatoes and 1 1/2 tsp oregano and cook for 1 min. Stir in the spinach, put the lid on the pan and leave for a few mins to wilt.

Add the flour and stir through until combined. Pour in the milk, stir gently and bring to the boil. Bubble for a few mins, then stir in the cheese and season. Cook until the cheese has melted and the sauce has thickened.

Mix the mash with the remaining oregano and spread over the filling. Scatter over a little more grated cheese and bake for 10-15 mins until golden. The top can also be grilled rather than baked, but keep an eye on it as you may need to reduce the cooking time.