For CrustCombine flour, sugar, and salt in the basin of a food processor.2 ½ cups (310 g) all-purpose flour, 1 Tablespoon granulated sugar, ½ teaspoon table saltScatter butter pieces evenly over the surface of the flour mixture and pulse until the butter is cut into the mixture and your mixture resembles coarse crumbs. You should still see some pieces of butter remaining, some may be as large as chocolate chips, this is fine!1 cup (226 g) unsalted butterAdd sour cream and pulse until sour cream is incorporated, flour is absorbed, and mixture is beginning to cling together.½ cup (120 g) sour creamRemove dough from food processor (be careful of the blade!) and transfer to a piece of plastic wrap. Form into a ball then flatten into a disk. Chill for at least 30-60 minutes before rolling out. In the meantime, prepare your filling.

For FillingCombine sugar and cornstarch in a small saucepan and whisk together until combined.¼ cup granulated sugar, 2 teaspoons cornstarchAdd berries and lemon juice and stir to combine.8 oz (226 g) strawberries, 2 teaspoons lemon juiceTransfer saucepan to stovetop over medium-low heat and cook, stirring constantly, until the berries release their juices and begin to soften. Mash them with a potato masher or large fork until no large pieces remain.Stir while the mixture bubbles and cook until it begins to thicken and begins to approach a jelly-like consistency. Note that the filling will continue to thicken as it cools.Once the filling begins to thicken, remove from heat and stir in butter until completely combined. Set aside and allow to cool completely before filling pastry (you can speed up the process by placing the filling in the refrigerator).½ Tablespoon butter

AssemblyOnce dough has chilled and filling has cooled, preheat oven to 400F (205C) and line a baking sheet with parchment paper.Prepare egg wash by thoroughly whisking together egg and water.1 large egg, 1 teaspoon waterTransfer pie crust to a clean, lightly floured surface and dust with additional flour as needed. Roll dough into a rectangle about ⅛-¼” thick then cut into 2.5”x4” (6x10cm) rectangles (I use a rectangular cookie cutter to do this, but you can just use a sharp knife or a pizza wheel!).Place one rectangle on prepared baking sheet and lightly brush the surface with egg wash. Drop a rounded Tablespoon of strawberry filling into the center, then top with another rectangle of dough. Use a fork to crimp the sides to seal, then brush the surface of the dough with egg wash. Use a toothpick or wooden skewer to poke 6-8 holes in the surface of the pop tart to allow it to vent.Repeat steps above until you have formed all of your pop tarts, then transfer to 400F (205C) oven and bake 15-17 minutes and beginning to turn golden brown. Allow pop tarts to cool on baking sheet before decorating with icing.

IcingCombine sugar, 1 Tablespoon of milk, corn syrup, and vanilla extract and whisk until combined. If mixture is too thick, add remaining milk as needed until smooth (if icing becomes too thin, you can always thicken it with a bit more powdered sugar). Icing has reached ideal consistency when you lift the spoon from the icing and the ribbon that drizzles off the spoon holds its shape for several seconds before dissolving back in the bowl.1 ½ cups (190 g) powdered sugar, 2 Tablespoons milk, 1 Tablespoon light corn syrup, ¼ teaspoon vanilla extractDrizzle icing over the center of the pop tarts and top with sprinkles, if using. Allow frosting to harden before serving and enjoying.Nonpareils