Preheat the oven to 180°C / 160°C (fan oven) / 360°F / Gas Mark 4. Lightly spray baking sheets with the cooking spray.

Unroll the filo pastry sheets, and cut them into 8 equal squares. Layer the squares on the baking sheet in 8 piles, misting each layer of pastry with a little of cooking spray, and offsetting the squares as you layer them to make a rough circle.

Reserve 1 tablespoon of beaten egg, then mix the rest with the ground almonds and sugar. Divide the mixture between the pastry circles, spreading it into the middle to leave a border round the edge. Top the almond mixture with the sliced plums. Brush the pastry borders with the reserved egg and scrunch up the pastry a little around the filling.

Bake for 20-25 minutes, until the pastry is golden brown. Serve the tarts warm, sprinkled with a little icing sugar.