Preheat the oven to 375ºF. Line an 11-inch by 17-inch baking sheet with parchment paper.

Place the dough on a generously floured counter or cutting board. Sprinkle more flour on top. Roll the dough out to 1/8-inch thickness, making sure to lift it off the board every few rolls to ensure it’s not sticking (add more flour as needed—it’s okay to be generous with it). Trim any rough edges with a knife or pizza cutter (pro-tip!). Cut the rectangle into 12 to 16 even-sized rectangles. You can also divide the dough in half, and roll it out in batches, and feel free to reroll the scraps.

Place half the pastry pieces on the prepared pan. Spoon 2 teaspoons of jam into the center. Spread the jam out, leaving a ½-inch border. Cover each pastry with one of the remaining plain pieces of pastry. Use a fork to crimp the edges closed. Use a pizza wheel or pastry cutter if you want a really neat edge.

Bake until crisp and golden around the edges, about 15 minutes. Transfer to a wire rack to cool completely (take care as they will be delicate when first out of the oven).

Add the blueberries to a ziptop bag. Use a rolling to crush them.

Add the Confectioner’s sugar to a small, deep bowl with the almond extract and 4 to 6 teaspoons of cold water. Whisk until smooth. Drizzle over the cooled tarts, or spread it on with an offset spatula. Decorate with crushed freeze-dried blueberries. Let the icing set for at least 30 minutes before serving, or packing if giving as a gift.