Homemade Pop Tarts

Name: Homemade Pop Tarts
Ingredients: 4 sticks unsalted butter (1 pound), cubed; 4 1/2 cups all-purpose flour, plus more for dusting; 1 tablespoon granulated sugar; 2/3 cups plus 2 tablespoons water; 4 teaspoon apple cider vinegar; 2 3/4 teaspoon kosher salt; 1/2 cup finely chopped strawberries; 1/2 cup strawberry jam; 1 tablespoon cornstarch dissolved in 1 tablespoon water; 1 large egg; 1 box (1-pound) confectioners’ sugar; 6 tablespoons milk; 1/4 teaspoon pure vanilla extract; Rainbow sprinkles, for decorating