Preheat oven to 350 degrees and line a baking sheet with parchment paper.
In a large bowl, mix together the flour, baking soda, salt, and baking powder. Set aside.
In a separate bowl, beat together the butter, cream cheese, and sugar until light and fluffy.
Add the vanilla, egg, and two to three drops of purple gel food coloring. Beat until well combined.
Slowly add the dry ingredients and mix until well combined. A spoon may be needed to mix in the last of the flour if the dough is too thick for a mixer.
Scoop heaping tablespoons of dough from the bowl and roll into a ball. Dip the balls into the Halloween sprinkles, leaving the bottom free of sprinkles.
Place each rolled cookie on the prepared baking sheet and press the balls down slightly with the bottom of a cup. Press candy eyes into the tops of the cookies.
Bake in the preheated oven for 10 to 12 minutes, until the bottom of the cookies are beginning to brown.
Remove from oven and allow to cool on the baking sheet for five minutes, then transfer to a wire cooling rack to cool completely before serving.