Preheat the oven to 350 degrees and line a baking sheet with parchment paper.
In a mixing bowl, beat the softened butter and sugar until smooth and creamy.
Stir in the vanilla extract until combined.
Add the flour, cocoa powder, and salt to the bowl. Mix until a soft dough forms.
Place the dough on a lightly floured surface and roll it to about 1/4 inch thick.
Cut bat wing shapes using a knife or cookie cutter and place them on the baking sheet.
Bake for 10 to 12 minutes until the edges look set. Let the cookies cool on the sheet for 5 minutes before moving them to a rack.