This is the BEST Oreo cake because I use a scale so it turns out perfectly. 🙂 If you convert to cups I cannot guarantee good results. Make sure your (cold ingredients) butter, eggs, and milk are at room temperature or a little warm.I microwave my milk for about 30 seconds and place my eggs (still in the shells) in a bowl of warm water for 5 minutes. Preheat your oven to 335ºF (168ºC) and prepare three, 6"x2" cake pans with cake goop or another preferred pan release.
In a large bowl, combine flour, baking powder, and salt. Set aside.
Combine the milk, oil, and vanilla extract in a separate cup. Set aside.
Place the softened butter in a stand mixer with a paddle attachment and cream until smooth. Sprinkle in your sugar and then let whip on medium-high until light, white, and fluffy (about 5 minutes).I'm using my Bosch Universal Plus stand mixer, a KitchenAid will work as well. I wouldn't recommend using a hand mixer but if that's all you have, make sure to go by look and consistency instead of time. (See pictures above.)
While mixing on low, slowly add the egg whites to the mixture one at a time, letting each fully combine before adding the next. (Cold egg whites will curdle the batter, so make sure they're room-temperature.)
Add in 1/3 of your dry ingredients to the mixture and mix on low until just combined. Then add in 1/2 of your liquids, then 1/3 dry, then 1/2 liquids, and the rest of your dry. Let it mix until just combined. Do not overmix!
Scrape the cream filling from the Oreos and discard or save and mix into your Oreo frosting, then roughly chop the oreos into 1/4-inch chunks. Divide the batter evenly into prepared cake pans and sprinkle the chopped oreos on top of each pan. Gently fold the oreos into the batter with a knife until just combined. Bake cakes at 335º F for 35-45 minutes or until a toothpick comes out clean when poked in the center.If you're using two, 8"x2" pans, bake for longer.
Let the cakes cool in the pan for 10 minutes or until the pan feels barely warm then turn out cakes onto a cooling rack. Place them into the freezer to flash chill, or wrap in plastic wrap and freeze for up to 1 week. This locks in the moisture.
Once cool, you can then trim off the brown edges and domes of your cakes (optional) and frost as desired. I do a crumb coat, freeze the cake for 15 minutes, then do a final coat, combine my leftover buttercream with the crushed Oreos, and top the cake with some dollops and whole oreos.