Individual pies with blueberry-peach filling

Ingredients:

• 2 medium peaches, peeled and diced (about 2 cups)
• 1 cup blueberries
• 2-3 tablespoons of granulated sugar
• 2 tsp cornstarch
• 1/8 tsp. grated nutmeg
• 2 teaspoons lemon juice
• One 400g pack of chilled cakes for 2 pies
• 1 large egg, beaten
• 1 tbsp cold butter, cut into pieces
• Demerara sugar, for sprinkling
• Flour, for rolling out
• Special device6 Mason jar lids with wide mouths, about 3.5 inches in diameter; a 4- to 5-inch round pastry cutter, optional

Preparation:

1. Preheat oven to 350°F (190°C). Line a baking sheet with parchment paper. Place 6 Mason jar lids (9 cm in diameter) upside down on the baking sheet, then lightly spray with nonstick spray.
2. In a medium bowl, combine the peaches, blueberries, sugar, cornstarch, nutmeg, and a pinch of salt. Sprinkle with lemon juice and mix again. Set aside and let sit at room temperature while you roll out the cake layers.
3. Roll out one cake layer on a lightly floured surface. Use a round pastry cutter to cut out 6 bottom layers (or simply cut out circles slightly larger than the lids).
   
   Fill the prepared lids with the cake layers and press the dough around the edges so that it extends slightly beyond the lids. Roll out the second cake layer and cut out six top layers. Make three slits in each layer to allow steam to escape.
4. Divide the filling between the six bottom layers and lightly brush the edges with beaten egg. Top with butter, cover with slit layers, and pinch the edges shut. Lightly brush the top with beaten egg and sprinkle with demerara sugar.
5. Bake on the prepared baking sheet until the crust is golden brown and the filling is bubbly, about 30 minutes. Let cool for at least 20 minutes before serving. To remove the pies from the lids, press the bottom of each lid and push the pie out. Serve.