Preheat the oven to 350F then line a large baking sheet with parchement paper and set aside.
In a large bowl, cream the butter, brown sugar and granulated sugar together.
Add in the egg, vanilla butter emulsion, and cake batter flavoring and mix until combined.
Add in the flour, corn starch, baking soda, and salt and mix just until the flour mixture disappears. Fold in the white chocolate chips.
Using a large cookie scooper, scoop out 9 equally sized cookies dough balls. Roll the sides of each cookie in the rainbow sprinkles, place on the prepared baking sheet and gently flatten with your hand to about ¾-1 inch in thickness.
Bake the cookies in the preheated oven for 11-12 minutes then let them cool down on the baking sheet for 10 minutes before transferring them to a cooling rack.
Enjoy with a tall glass of cold milk!