Preheat your oven to 450 degrees F. Place one refrigerated pie crust onto the prepared baking sheet. Prick it gently with a fork to allow steam to escape.
Spread the strawberry jam evenly across the center of the crust, leaving about a half-inch border around all sides.
Carefully place the second pie crust over the jam. Seal the edges by pressing firmly with the tines of a fork all the way around the pastry. Use a fork to gently prick holes in the top crust.
Brush the entire surface with egg wash (a mixture of scrambled egg and water).
Bake for 12-15 minutes, or until the pastry is deep golden brown and the filling is bubbling slightly around the edges. Allow the giant pop tart to cool completely before glazing.
In a small bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth.
Drizzle or spread the vanilla glaze across the cooled pastry. Pour sprinkles over the top if desired. Allow the icing to set for several minutes before slicing.
