01 -
Preheat the oven to 325°F and grease and flour three 6-inch cake pans or two 8 or 9-inch cake pans. Set aside.
02 -
Separate the Oreos, scrape off the cream, and place just the cookies in a plastic bag. Use a rolling pin to crush the cookies into small pieces.
03 -
In a large mixing bowl fitted with a whisk attachment, beat the softened butter and oil together until they become homogenous, about 3 minutes. Ensure the butter is at true room temperature.
04 -
Slowly add the granulated sugar to the butter and oil mixture. Beat on high until light, fluffy, and pale yellow, about 3 minutes.
05 -
Add the eggs one at a time along with the vanilla, scraping down the bowl in between each addition. Beat on high for 3 more minutes to incorporate air.
06 -
In a separate bowl, sift together the cake flour, salt, and baking powder. Alternate mixing in the dry ingredients and buttermilk in 4 batches, starting with the buttermilk and ending with the dry ingredients. Do not overmix; it’s fine if a few lumps remain. Fold in the crushed Oreo pieces.
07 -
Divide the batter evenly among the prepared pans and bake for 30 minutes or until golden brown. A clean knife or skewer should come out clean when inserted. Cool on a rack.
08 -
In a mixing bowl, cream the butter, powdered sugar, milk, vanilla extract, and salt together. Beat until light and fluffy, about 1 minute.
09 -
Add the espresso powder one tablespoon at a time to achieve your desired coffee flavor. Use 2 tablespoons for a mild coffee flavor or 3 for a stronger taste. Fold in the crushed Oreos by hand to maintain texture.
10 -
Place the first cake layer on a stand. Top with a generous amount of frosting. Repeat for the second and third layers, ensuring even distribution of frosting. Use remaining frosting to cover the sides and top of the cake.