Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
In a mixing bowl, combine the flour, sugar, and salt. Add the cold vegan butter and use a pastry cutter or your hands to mix until the mixture resembles coarse crumbs.
Add the ice water, one tablespoon at a time, until the dough comes together. Form the dough into a ball, wrap it in plastic wrap, and refrigerate for 30 minutes.
Roll out the dough on a lightly floured surface to about ⅛-inch thickness. Cut the dough into rectangles (about 3x4 inches).
Place a tablespoon of fruit jam in the center of half of the rectangles. Top with the remaining rectangles and press the edges with a fork to seal.
Place the pop tarts on the prepared baking sheet and bake for 20-25 minutes, or until golden brown. Let them cool completely.
In a small bowl, mix the powdered sugar, non-dairy milk, and vanilla extract to make the icing. Drizzle over the cooled pop tarts.