Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a large mixing bowl, cream butter and sugar until light and fluffy.
Add egg and vanilla extract. Mix until fully combined.
Gradually add flour and baking powder, mixing until dough forms.
Divide dough and add food coloring if desired.
Roll out dough on a floured surface. Use Halloween cookie cutters to shape.
Place on baking sheet and bake for 8–10 minutes.
Let cookies cool on a wire rack before decorating with icing and sprinkles.