In a large bowl, cream together the softened butter and granulated sugar until light and fluffy, then beat in the egg and vanilla extract.

In a separate bowl, whisk together the flour, baking powder, and salt, then gradually add the dry ingredients to the wet ingredients until just combined and a soft dough forms.

Roll out the dough on a lightly floured surface to about 1/4-inch thickness, then cut into Halloween shapes using cookie cutters and place them on baking sheets lined with parchment paper.

Preheat your oven to 375°F (190°C) and bake the cookies for 8-10 minutes, or until the edges are lightly golden.

Allow the cookies to cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely, then decorate as desired with icing and sprinkles.