Sift together the flour, caster sugar, and pumpkin spice. Cut in the dairy-free butter until it resembles coarse crumbs. Gradually add ice water until the dough comes together. Refrigerate for 30 minutes.

Roll the dough between two sheets of floured greaseproof paper until 1/8 inch thick. Cut out shapes using pumpkin-shaped cookie cutters and place on a parchment-lined baking sheet.

Combine pumpkin puree, maple syrup, pumpkin spice, and cornstarch in a bowl. Stir until smooth to make the filling.

Place a dollop of pumpkin filling on half of the pastry shapes. Brush edges with dairy-free milk, top with remaining pastry shapes, and crimp edges with a fork.

Preheat oven to 180°C (350°F). Brush tops with dairy-free milk and bake for 15-20 minutes until golden brown.

Mix icing sugar, maple syrup, pumpkin puree, and dairy-free milk until thick yet pourable. Adjust as needed for consistency.

Drizzle the glaze over the cooled pop tarts and let set for a few minutes before serving.