Preheat the oven to 325°F. Prepare a 9×13 inch baking pan with baking spray.

Toss the sprinkles with 2 tablespoons of flour and set aside.

Combine the remaining flour, baking powder, baking soda, and salt in a medium bowl.

In a large mixer bowl, cream butter and sugar until light and fluffy, about 3 minutes.

Add egg yolks one at a time, mixing well after each addition. Scrape down the sides of the bowl.

Add the dry ingredients to the batter in thirds, alternating with milk, starting and ending with dry ingredients. Mix until just combined.

Fold in sour cream until combined. Gently fold in the sprinkles.

Pour batter into prepared baking pan and bake for 40-45 minutes. Cool before frosting.