1-First Steps: Begin by mixing your filling: combine 2 cups of fresh blueberries, 1/4 cup granulated sugar, 1 tablespoon cornstarch, the zest of 1 lemon, 1 tablespoon lemon juice, 1/2 teaspoon vanilla extract, and 1/4 teaspoon ground cinnamon in a pan. Cook this mixture over medium heat for 5-7 minutes until it thickens up nicely, then let it cool down. While it cools, roll out your 2 sheets of thawed puff pastry on a floured surface and cut each into 4 squares, giving you 8 squares in total.

2-Assembling the Turnovers: Once your filling is ready, spoon it onto the center of each puff pastry square. Brush the edges with a beaten egg to help seal them, then derogatory fold each square into a triangle and crimp the edges with a fork for a tight seal. This step ensures the filling stays inside during baking, avoiding any messy leaks.

Place the turnovers on your prepared baking sheet and brush the tops with the egg wash for that golden finish. Pop them in the preheated oven and bake for about 20 minutes until they’re puffed up and a beautiful golden brown. After baking, let them cool on a wire rack to set before you dig in, keeping the flaky texture intact.