In a large mixing bowl, cut the chilled vegan butter into the all-purpose flour using a pastry cutter until coarse crumbs form.

Gradually add ice water, mixing gently until the dough just comes together, then refrigerate for about 30 minutes.

Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.

Roll out the dough on a floured surface to about ⅛ inch thick and use a ghost-shaped cookie cutter to cut out shapes.

Place half of the cutouts onto the baking sheet, spoon blueberry jam onto each, top with another cutout, and seal the edges.

Bake for 20–25 minutes until golden brown, cool them on a wire rack.

Whisk together powdered sugar and plant-based milk for the glaze and drizzle generously over the cooled tarts.

Decorate with black gel or melted chocolate to create ghost faces, if desired.