In a large bowl or the bowl of a stand mixer, with an electric mixer or paddle attachment, add the butter and sugar to a mixing bowl and beat until smooth and creamy.
Add the egg and vanilla extract and beat until combined.
In a separate bowl, whisk together the flour, baking powder, corn starch and salt.
Add the dry ingredients to the wet ingredients and fold together until combined into a smooth dough.
Shape the dough into a ball with your hands, cover in plastic wrap and place in the fridge to chill for 1 hour.
Preheat the oven to 350 degrees F and line two baking sheets with parchment paper. Roll out the dough out with a rolling pin to approximately ¼” thickness and cut out shapes using your Halloween cookie cutters.
Place the cut out cookie shapes on the prepared baking sheets and bake for 8-10 minutes or until the edges start to turn golden brown.
Leave on the baking sheets for about 10 minutes, then transfer to a wire rack to cool completely.