Cream together butter and cream cheese until well combined.
Add ½ cup sugar and ¼ cup brown sugar and cream together until light and fluffy.
Add in the egg white and ½ tsp vanilla and beat until combined.
Add in 1¾ cup flour, ½ tsp cornstarch, ½ tsp baking soda, ¼ tsp salt, and mix until combined.
Fold in the vanilla funfetti chips, chocolate chunks, and 2 Tbsp sprinkles (reserving some sprinkles for topping).
Scoop into 1½" balls and chill for 30 minutes - 1 hour.
Remove from the fridge and flatten slightly. Press extra sprinkles onto the top as desired.
Bake for 8-10 minutes or until lightly browned. Remove from the oven and allow to cool before serving.