In a large mixing bowl, cream together the room temperature butter and oil for about 2-3 minutes until smooth and well combined.

Gradually add in the sugar, continuing to beat until fluffy and light in color.

Incorporate the eggs one at a time, mixing well after each addition.

Pour in the vanilla extract and blend until combined.

In a separate bowl, whisk together the cake flour, salt, and baking powder.

Gradually add this mixture to the wet ingredients, alternating with the buttermilk.

Fold in the crushed Oreos gently into the cake batter.

Preheat your oven to 350°F (175°C).

Divide the batter into two prepared eight-inch cake pans and bake for 30-35 minutes.

Allow cakes to cool in the pans for about 10 minutes before transferring to wire racks to cool completely.

Beat the softened butter in a mixing bowl until creamy.

Gradually add powdered sugar and espresso powder, alternating with milk until smooth.

To assemble, place one layer on a serving plate, spread coffee Oreo frosting on top, and add the second layer.

Frost the top and sides of the cake with remaining frosting.