Preheat the oven to 425°F (220°C/Gas 7)

Put the red pepper, onion, courgettes, garlic, and olive oil into a large roasting tin; season with the chopped anchovy fillets (if you are including them), salt, and pepper to taste, and toss together.

Spread the vegetables out and roast on the top shelf of the oven for 15 minutes. Remove, turn them over and return to the oven for another 10 minutes or until tender.

Remove and leave to go cold.

On a lightly floured surface, roll out the pastry until it is about ¼ inch thick, then cut into 4 x 6 inch discs and 4 x 5½ inch discs (saucers work fine for this) – roll the pastry a little more if necessary.

Spread the red pesto over the center of each 14cm disc to within 2cm of the edge. Spoon the roasted vegetables on top, sprinkle with basil, and top with a quarter of the mozzarella.

Beat the egg yolks with 2 teaspoon of cold water. Brush some of the mixture around the edge of each base; lay the larger discs on top and press the edges together to seal, and score with the tines of a fork.

Place the Pithiviers on a buttered non-stick baking sheet and chill for at least 20 minutes.

The recipe up to this point can be made up to a day in advance.

Brush the top of each Pithivier with the remaining egg yolk glaze, then score the pastry lightly with the tip of a sharp knife to decorate. Make a small slit in the center of each to let out steam.

Bake in the center of the oven for 20 minutes until puffed up and golden!