1. Preheat oven to 350°F (176°C). Spray a cupcake pan with non stick cooking spray.
2. Cream butter and sugars together until light and fluffy, about 3-4 minutes.
3. Mix in egg and vanilla extract.
4. Combine the flour, baking soda, cornstarch and salt in a medium sized bowl, then add to the butter mixture. Mix until well combined and a dough forms.
5. Stir in the chocolate chips, M&Ms and sprinkles. Dough will be thick and a bit sticky.
6. Makes balls of about 2 tbsp of dough. Press cookie dough into the bottom and about 1/3-1/2 way up the sides of each cupcake cup, forming a cup shape.
7. Bake for 10-12 minutes, or until edges are just golden. If they look a little undercooked in the center, that’s ok. They’ll continue to bake as they cool and firm up.
8. Remove from oven and allow to cool mostly in the pans, then remove to a cooling rack. If the centers aren’t cupped enough, use the bottom of a tablespoon to press the center down a bit while still warm.
9. To make the frosting, beat the butter and shortening together until smooth.
10. Slowly add half of the powdered sugar and mix until smooth.
11. Add the vanilla extract and 1-2 tablespoons of water or milk and mix until smooth.
12. Slowly add the remaining powdered sugar and mix until smooth. Add additional water or milk, as needed.
13. Split the frosting into two bowls and color one bowl with red gel icing color.
14. Put the two colors of frosting into two separate smaller piping bags, then put both piping bags side by side in a larger piping bag fitted with a piping tip. I used Ateco tip 844.
15. Pipe the frosting into the cookie cups and top with sprinkles.