Prep the pastry: Preheat your oven to 400°F (200°C). On a lightly floured surface, roll out the puff pastry sheet into a roughly 12×12-inch square. Cut into 9 equal squares. Use a knife to lightly score a smaller square about ½ inch inside each piece (don’t cut all the way through)—this will help create a raised border.

Make the chocolate ganache: Heat the heavy cream in a small saucepan until it just begins to simmer. Pour it over the chopped chocolate and let it sit for 2 minutes. Stir gently until smooth and glossy. Stir in the butter until melted and combined.

Assemble the tarts: Place puff pastry squares on a parchment-lined baking sheet. Brush the edges lightly with beaten egg for a golden finish. Spoon a tablespoon of ganache into the center of each square, inside the scored border.

Bake: Bake for 12–15 minutes or until the pastry is puffed and golden. Remove from the oven and gently press a few fresh raspberries onto the ganache while it’s still warm.

Cool and serve: Let the tarts cool slightly on a wire rack. Dust with powdered sugar if you want to get fancy before serving.