To make the pastry, put the flour and butter into the bowl of a food processor with a little seasoning. Whizz until the mixture resembles breadcrumbs. Add the egg and 1 tablespoon of water and whizz until the mixture forms a ball.

Roll out the pastry on a clean, lightly floured work surface to 5 mm (¼ in) thick, then cut into 24 rounds using a 5 cm (2 in) fluted round cutter. Line each hole of 2 x 12-hole deep mini bun tins with the pastry circles and prick the bases with a fork. Chill in the fridge.

Preheat the oven to 200°C/400°F/Gas 6.

To make the filling, heat the olive oil in a saucepan over a low heat. Add the onion and sauté for 5 minutes until soft. Add the thyme leaves, season to taste and leave to cool. Whisk the eggs and cream together in a jug.

Remove the pastry from the fridge and divide the cooked onion evenly between the pastry cases. Top each with a cherry tomato half, cut side up. Pour over the egg and cream mixture and sprinkle the Parmesan cheese over the tarts. Bake the tarts for about 15 minutes, until golden on top and crisp underneath.