In a large bowl, stir together the flour, sugar, and salt. Add in the cold butter and use a pastry cutter or your fingers to blend until the mixture forms coarse crumbs.

Whisk one egg with the milk in a small bowl. Pour into the flour mixture and mix just until the dough holds together.

Divide the dough in half, shape into discs, wrap each in plastic, and refrigerate for 30 minutes.

Roll out one disc of dough on a lightly floured surface into a 1/8-inch thick rectangle. Trim edges and cut into 9 equal rectangles.

Repeat with the second disc to create 9 matching tops.

Place the bottom rectangles on a parchment-lined baking sheet. Spoon about 1 tablespoon of jam into the center of each, leaving a clean border around the edges.

Beat the second egg and lightly brush the borders with it. Top each with a second rectangle of dough and press the edges to seal. Crimp with a fork.

Poke holes in the tops to allow steam to escape. Refrigerate the assembled tarts for 30 minutes.

Preheat the oven to 375°F (190°C). Bake the Pop Tarts until golden brown, about 30 minutes.

Let cool completely on a wire rack. For the glaze, stir together the powdered sugar, heavy cream, and vanilla until smooth. Spread over cooled tarts and let set before serving.