• Preheat the oven to 350°.

Cookies

• Combine the butter and butter flavored shortening in a large bowl and mix together using a hand held {or stand} mixer until creamy. Add the eggs and vanilla to the butter mixture and continue to mix until combined.
• Finally, add the white cake mix, flour and corn starch to the wet ingredients and mix until you have a thick sugar cookie dough.
• Use a medium cookie scoop to measure out cookie dough into your hand. Roll the dough into a smooth ball and place onto a silicone mat {or parchment} lined baking sheet.  Then form the smooth cookie dough balls into a round disc.
• Bake for 9-11 minutes or until the cookies are baked through but not over baked. Remove from the oven and move the cookies to a cooling rack. Continue until all of the cookies are baked.

Frosting

• While the cookies are cooling combine the butter and butter flavored shortening in a medium bowl. Mix with a hand held mixer {or by hand} until light and fluffy. Add powdered sugar, vanilla extract and milk. Mix until you have a smooth and thick frosting. Use a little more milk to thin out frosting, if needed. Add a few drops of pink food coloring and mix until you have an even pink color.
• Either spread the frosting on each cookie with an off-set spatula or put the frosting in a piping bag and pipe the frosting in a thick layer on top of each cookie. Top with rainbow sprinkles and press them down lightly. Allow the frosting to set up for about an hour before stacking the cookies.