homemade pop tarts

INGREDIENTS

• 2 cups (8 1/2 ounces) all-purpose flour
• 1 tablespoon sugar
• 1 teaspoon salt
• 1 cup (2 sticks or 8 ounces) unsalted butter, cut into pats
• 1 large egg
• 2 tablespoons (1 ounce) milk
• 1 additional large egg (to brush on pastry)
• (enough for 9 tarts)
• 1/2 cup (3 3/4 ounces) brown sugar
• 1 to 1 1/2 teaspoons ground cinnamon, to taste
• 4 teaspoons all-purpose flour
• 1 large egg, to brush on pastry before filling
• 3/4 cup (8 ounces) jam
• 1 tablespoon cornstarch mixed with 1 tablespoon cold water
• 9 tablespoons chocolate chips, 9 tablespoons Nutella or other chocolate-hazelnut paste or 9 tablespoons of a delight of your choice, such as salted caramel or a nut paste