- Preheat the oven to 230°C/gas 8. To make the pastry, combine the flour, sesame seeds and a pinch of salt in a bowl, then rub in the spread with your fingertips. When the mixture resembles breadcrumbs, stir in 4–5 tbsp iced water, or as much as is needed, with a round-bladed knife, to form the mixture into a soft dough. (If preferred, use a food processor to make the pastry.) Wrap with cling film or greaseproof paper and chill for 15–20 minutes.
- Meanwhile, cut the squash lengthways into wedges and discard the seeds and stringy fibres. Peel away the skin and cut the flesh into 3cm dice. Cut the pepper into squares, slightly smaller than the squash. Put the vegetables into a roasting tin, drizzle over the olive oil, sprinkle with freshly ground black pepper and toss together.
- Roast the vegetables for 30 minutes until browned. Remove and leave to cool. Reduce the oven temperature to 180°C/gas 4. Put a baking tray into the oven to heat.
- Unwrap the pastry and roll out on a floured work surface to a circle about 25cm round. Lift it over a 21cm flan tin and gently press the pastry onto the base and sides. Trim off the excess.
- In a wide jug or mixing bowl, combine the eggs with the milk and cheese. Season with the chillies or pepper. Spoon the roasted vegetables into the pastry case, mounding them in the centre, then pour over the cheesy egg custard.
- Set the tin on the heated baking tray and bake for 25 minutes until just set, puffed and golden. Remove from the oven and leave to stand for 5 minutes before serving. Eat warm from the oven or at room temperature.
Parmesan cheese is not truly vegetarian, as it contains animal rennet. To make this dish 100% vegetarian, omit the cheese or find a suitable vegetarian substitute made without animal rennet. In supermarkets look for the 'parmesan style hard cheeses' which are suitable for vegetarians.
Use a pumpkin instead of butternut squash. You'll need about 700g prepared flesh. * Replace half the butternut squash with diced courgettes and green peppers.
The tart can be made ahead, then gently warmed before serving.