For a large bat, cut a chocolate-flavored breakfast pastry in half diagonally. For a small bat, cut a chocolate-flavored breakfast pastry in half diagonally and then in half again, making four triangles.
To make a bat, carefully dip one side of two pastry triangles into melted semisweet chocolate. Place triangles, chocolate sides up, on a baking sheet lined with waxed paper. Embellish triangle wings with decorative sprinkles.
Dip a chocolate, cream-filled sandwich cookie (large for a large bat and miniature for a small bat) into melted chocolate. Place a cookie body on top of the triangle wings. Add eyes of almonds, sunflower kernels, and/or pumpkin seeds. For the almond eyes, use miniature chocolate pieces as pupils. Chill until chocolate is set.