Preheat your oven to 350°F (175°C) and prepare your cake pans by greasing and lightly flouring two 9-inch round pans.

Whisk together the all-purpose flour, baking powder, and a pinch of salt in a medium bowl until well combined.

Cream the unsalted butter and granulated sugar in a large mixing bowl until light and fluffy, about 3-5 minutes. Scrape down the sides, then add the eggs one at a time followed by the pure vanilla extract, stirring until well blended.

Combine the dry flour mixture with the wet ingredients, alternating with the whole milk until just mixed. Fold in the rainbow sprinkles.

Pour the batter evenly into the prepared pans and bake for 25-30 minutes, or until a toothpick comes out clean. Allow the cakes to cool in the pans for about 10 minutes before transferring to a wire rack.