Preheat the oven to 350F then line a baking sheet with parchement paper and set it aside.

Add in the egg, cake batter extract, and vanilla extract and until combined.

Mix in the flour, baking powder, baking soda, salt, and sprinkles until the flour mixture disappears.

Use a large cookie scooper scoop out 6 equally sized cookie dough balls, place them on the baking sheet and gently flatten them to desired in thickness, these will not flatten much in the oven.

Bake the cookies in the oven for 10-12 minutes, then let them cool for 10 minutes before transferring to a cooling rack to cool down fully.

While the cookies are cooling make the birthday cake frosting

In a large bowl, cream the butter, powdered sugar and cake batter extract and mix until fluffy.

Place the frosting in a piping bag and frost each cookie and top with sprinkles.