Chocolate Hazelnut Pie

Prepare the Filling: In a mixer, beat the butter and sugar together until creamy. Add the ground hazelnuts and cornstarch, mixing until well combined. Gradually add the eggs, one at a time, continuing to beat until the mixture becomes light and fluffy. Stir in a small amount of the melted chocolate into the butter mixture, then fold the rest of the chocolate into the mixture.

Assemble the Pie: Place one sheet of puff pastry on a baking tray lined with parchment paper. Spread the chocolate hazelnut mixture evenly over the pastry, leaving a 2 cm border around the edges. Cover with the second sheet of puff pastry. Press the edges firmly with your fingers to seal the two layers together. Brush the top with the egg mixed with milk. Chill in the refrigerator for about 1 hour.

Bake the Pie: Use a fork to lightly score the surface of the pie in a diagonal pattern. Bake in a preheated oven at 170°C (340°F) for about 45 minutes, or until the pie is golden brown. Allow the pie to cool slightly before slicing and serving.