Homemade Pop-Tarts

INGREDIENTS

• :
• 2 cups all-purpose flour
• 1 tablespoon granulated sugar
• 1 teaspoon salt
• 1 cup (2 sticks, or 8 ounces) unsalted butter, cold and cubed
• 1 egg
• 2 tablespoons milk
• ½ cup light brown sugar
• 1½ teaspoon ground cinnamon
• 4 teaspoons all-purpose flour
• ¾ cup strawberry jam (or whatever flavor you'd like)
• 1 tablespoon cornstarch
• 1 tablespoon water
• 1 egg, lightly beaten (to brush on pastry)