Preheat oven to 350 degrees F. Line a 9x9 baking pan with foil. Spray with Non-Stick spray. Set aside.
Cream butter and sugar until smooth. Beat in eggs, and vanilla.
In a separate bowl whisk flour, salt, baking powder, baking soda, and cornstarch until combined.
Gradually add dry ingredient mixture. Stir until combined, do not overmix.
Fold in sprinkles and chocolate chips.
Press the dough into the pan using greased hands. Bake 25-28 minutes or until lightly browned. Cool completely.