Cookies & Cream Oreo Cake

Cake

1. Preheat oven to 350°F. Line three 8-inch pans with circles of parchment paper on the bottom and spray with baking spray.
2. Combine sugar, oil, and butter in a large bowl. Beat on medium-high speed for 2-3 minutes until creamy and light.
3. Add the egg whites one at a time, beating well on medium speed and scraping the bottom and sides of the bowl with a spatula occasionally to make sure everything is mixing together evenly.
4. Add the sour cream and vanilla extract. Mix again until combined.
5. Add half of the flour along with the baking powder, baking soda, and salt. Mix on low speed just until mostly combined. Add the milk and mix again, followed by the remaining flour.
6. Use a spatula to fold in the broken up Oreos. Divide the batter evenly between the three pans (it should be about 2 cups of batter per pan).
7. Bake for 25-30 minutes until a toothpick or skewer inserted in the center of each cake comes out clean or with just a few crumbs on it. You can also bounce your finger on the top of the cake and it should spring right back.
8. Let the cakes cool for 5-10 minutes in the pans, then run a thin, sharp knife around the edges of the pan and invert them onto wire racks to cool completely.

Frosting

1. Break up 8 Oreos into quarters or halves and place them in a bowl with the heavy cream to soak while you work on the rest of the frosting. Set 6 whole Oreos aside for decorating.
2. Add the remaining whole Oreos (cream filling and all) to a food processor and pulse until they are fine crumbs. If there are any large pieces, they can clog a piping tip if you plan to pipe swirls onto the top of your cake. Set aside 1/2 cup of the crumbs for decorating.
3. Beat the butter in the bowl of a stand mixer for 2 minutes until creamy and light using the whisk attachment. Add the powdered sugar and mix on medium-low speed, scraping the bowl occasionally, until the sugar is incorporated into the butter.
4. Add the vanilla and salt, then beat the frosting for 5 minutes on medium-high speed, scraping the bottom and sides of the bowl occasionally, until fluffy and light.
5. Add the finely crushed Oreo crumbs along with the cream that has been used to soak the broken up Oreos. Reserve the soaked Oreos for assembling the cake. Beat the frosting until the cookie crumbs are evenly distributed.

Assembly

1. Place one of the cake layers on a cake stand and spread a layer of the frosting on it. Add half of the soaked Oreos on top of the frosting, then top with a little more frosting so the layer is level.
2. Add the next cake layer and repeat with more of the frosting and the remaining soaked Oreos. Add the final layer and stick the cake in the fridge or freezer for 30 minutes to help set the layers and make the cake easier to frost.
3. Spread most of the remaining buttercream around the top and sides of the cake using an offset spatula and cake scraper to smooth it out if you want a finished look. Use any leftover frosting to pipe swirls on top of the cake. You may not need all the frosting, but it's so aggravating to have not enough frosting rather than too much.
4. To decorate the sides of the cake with Oreo crumbs, cup some of the reserved crumbs in one hand and gently press them against the sides, turning the cake as you go. Some of the crumbs will fall onto the cake plate and those can be carefully scraped off and used to sprinkle on top of the cake. Decorate with the reserved whole Oreos. Refrigerate or freeze the cake for 30 minutes to set the frosting before slicing and serving.