Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans with butter or cooking spray, then dust with flour.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3-4 minutes.

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

Gradually add the flour mixture to the butter mixture, alternating with the milk, starting and ending with the flour mixture. Mix until just combined.

Gently fold in the rainbow sprinkles until evenly distributed.

Divide the batter evenly between the prepared cake pans and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

To make the whipped frosting, beat the heavy whipping cream in a large mixing bowl until soft peaks form. Gradually add the powdered sugar and vanilla extract, continuing to beat until stiff peaks form.

Once the cakes are completely cool, place one layer on a serving plate and spread a layer of whipped frosting on top. Add the second layer and frost the top and sides of the cake with the remaining frosting.

Decorate the top of the cake with additional rainbow sprinkles.