Brush 4 deep muffin tins with the melted butter. Cut a sheet of filo pastry in half, then across into 4 equal-sized squares. Use these filo squares to line 1 muffin tin, arranging at slightly different angles, pressing down well and tucking the pastry into the tin neatly. Repeat with the remaining pastry to line the other muffin tins.
Bake the filo pastry tartlets in a preheated oven, 190°C (375°F), Gas Mark 5, for 8–10 minutes or until golden. Carefully remove the tartlet cases from the tins and leave to cool on a wire rack.
Whip the cream and brown sugar lightly in a bowl, until it holds its shape. Spoon into the tartlet cases and top with the peaches and raspberries. Dust with icing sugar. Serve immediately.