Use eggs, butter, sour cream, and milk at room temperature (about 70°F) to ensure proper emulsification and create a tender, moist crumb with minimal mixing.

Reserve about 20% of your sprinkles and fold them in after filling the pan to prevent color bleeding into the batter and maintain vibrant confetti throughout.

Whisk flour, baking powder, and baking soda separately, then fold gently into the wet mixture to avoid developing gluten, which creates tough, dense cake rather than tender layers.

Beating butter and sugar until pale and fluffy incorporates air bubbles that create lift and a delicate crumb structure, resulting in a lighter, more professional-quality cake.

Allow the cake to cool in the pan for 15 minutes, then on a wire rack for at least 2 hours, to prevent the frosting from melting and sliding off and to ensure clean frosting lines.