Preheat the oven to 325 degrees. Prepare three 8-inch or four 6-inch round cake pans by lightly spraying the bottom of the pan with cooking spray. Line with parchment paper and spray again. Set aside.

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

In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, oil, and sugar on high until fluffy and smooth, about 4 minutes. With a rubber spatula, scrape the bottom and sides of the bowl.

Add the eggs and the egg whites, one at a time, beating on medium speed after each addition. I usually beat each egg for about 30 seconds. Scrape the bowl after each addition. Once all the eggs/egg whites are added, beat for 30 more seconds.

Add the sour cream and vanilla. Beat on medium low speed for a minute. If the mixture looks clumpy, don’t worry, once you add the flour mixture it will smooth out.

Turn the mixer on low and add ⅓ of the flour and ½ of the buttermilk to the butter mixture and mix ON LOW until almost incorporated. Add another ⅓ of the flour and the rest of the buttermilk. Mix just until a few streaks of flour remain, then add the rest of the flour mixture. Mix just until the flour streaks are mostly gone.

With a rubber spatula, fold in the sprinkles and the crushed Oreos.

Evenly distribute the cake batter among the three 8-inch or four 6-inch pans and bake for 25-28 minutes or until a toothpick comes out with just a few moist crumbs on it or until it starts to get a little golden brown on top.

Remove cakes from the oven and let them cool in the pans for 15 minutes before transferring them out of the pan and placing them on cooling racks.

When cakes are completely cooled, wrap each cake layer individually with plastic wrap and stick it in the refrigerator or freezer until you’re ready to frost.

In the bowl of a stand mixer fitted with a paddle attachment, cream the butter for about 3 minutes on medium speed until the color lightens.

Add the sifted powdered sugar and heavy cream. Mix on low, just until combined.

Add the vanilla and salt, and beat on medium speed for 3 more minutes. The frosting will become lighter in color and texture.

Add in the rainbow sprinkles and mix on low. If you want to dye your frosting pink, this is when you add the coloring. I add a tiny bit of ameri gel red.

Before spreading the frosting on your cake, spend a couple of minutes mixing the buttercream by hand with a wooden spoon or a rubber spatula to push out the air pockets.

Place the first cake layer, top side up. Add about 1 cup of frosting. Spread over the cake layer as evenly as possible to the edges of the cake.

Repeat this step until you get to the final cake layer, which you will lay top side down.

Apply a thin coat of buttercream around the entire cake to lock in the crumbs. Freeze for about 10 minutes.

After the crumb coat is set, continue frosting and decorating the cake. Decorate and garnish with Golden Oreo’s.