If using frozen puff pastry, thaw it on the counter for 30 minutes.

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

Roll out the puff pastry to ensure an even thickness.

Use bat cutters to cut shapes from the puff pastry, creating an even number of larger and smaller bats.

Remove the center from half of the large bats and half of the small bats using a smaller bat cutter.

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

Place the top layer of bats with cut-outs onto the bottom layer, matching up the edges.

Brush the top layer with egg wash.

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

Gently press into the center of each bat to create space for filling.

Lightly dust with powdered sugar.

Fill each bat with blueberry jam using a piping bag or small spoon.