Thaw frozen puff pastry on the counter for 30 minutes before use.

Preheat the oven to 400 degrees F and line a rimmed baking sheet with parchment paper.

Roll out the puff pastry on a lightly floured surface to ensure even thickness.

Use bat cutters to cut out bats from the puff pastry, ensuring an even number of bats.

Remove the centers from half of the larger and half of the smaller bats using a smaller cutter.

Lay the bottom layer bats on the prepared baking sheet and brush with egg wash.

Place the top layers with the cut-outs onto the bottom layers and match the edges.

Brush the top layer with egg wash.

Bake in the preheated oven for 12 minutes, or until golden brown.

Press down the center of each bat gently to create space for filling.

Dust with powdered sugar.

Heat blueberry jam in the microwave for 20 seconds, then fill a piping bag with it and pipe into the openings of the bats.

Serve alongside your favorite Halloween treats.