Nectarine Turnovers (Easy Nectarine Recipe)

Name: Nectarine Turnovers (Easy Nectarine Recipe)
Prep time: 30 min
Total time: 30 min
Cuisine: World Cuisine
Ingredients: 250 grams diced nectarines (about 1 1/2 – 1 3/4 cups, or 2-3 nectarines)*; 30 grams dark brown sugar (2 tablespoons, packed); 15 milliliters lemon juice (1 tablespoon); 5 grams cornflour/cornstarch (2 teaspoons); 1 teaspoon vanilla bean paste; 1/2 teaspoon ground cardamom; 1 sheet puff pastry, thawed according to package directions if frozen; 1 large egg, lightly beaten; Demerara sugar, for sprinkling