Preheat your oven to 350°F (180° C), then line a cookie sheet with parchment paper and set aside. The number of batches will depend on how large/small you want your cookies.
Combine the flour, cornstarch, baking powder, and salt in a medium-sized bowl and set aside.
Cream the butter and sugar together in a large bowl with an electric mixer on medium speed until light in color and fluffy. Add cream cheese and vanilla and mix until well combined.
Add the flour mixture and mix until the dough comes together and is combined.
Add 3 – 4 drops of your chosen food coloring, is using, and mix until well incorporated. Do not over mix.
Form cookie dough into balls, about 1 ½ tablespoon each. For evenly sized cookies I like to use a small spring-loaded ice cream scoop to spoon out the dough.
Roll cookie dough balls in Halloween sprinkles until completely covered. These cookies don't spread much so I recommend to slightly flatten cookie with your fingers. At this point, you can bake the cookies right away or refrigerate for up to 3 days.
Bake for 10 -12 minutes, until very lightly colored on top and around the edges. If desired, press 1 or 2 candy eyes into the freshly baked cookies. Allow to cool on baking sheet for 5 minutes, then transfer to a wire rack to cool.