For the cake: Preheat the oven to 350 degrees F. Grease two 8-inch cake pans with butter.
Dissolve the espresso powder in 1/4 cup hot water, then stir into the orange juice. Set aside.
In the bowl of a stand mixer fitted with the whisk attachment, sift the cake flour, sugar, cocoa, baking soda, baking powder and salt. Mix on a low speed. In a second bowl, lightly whisk together the oil, buttermilk and eggs; slowly add to the flour mixture. Increase the mixer speed and whisk until fully incorporated. Fold in the orange juice-coffee mixture.
Pour the batter into prepared cake pans. Bake until a toothpick inserted into the center of the cakes comes out clean, 20 to 25 minutes.
For the cookies-and-cream filling: Combine the heavy cream and white chocolate in a microwave-safe bowl. Microwave for 1 minute, then stir until smooth. Set aside to cool.
In the bowl of a stand mixer fitted with the whisk attachment, whip the cream cheese, butter and vanilla until light and fluffy. Add the white chocolate mixture and whip for another minute. Lower the mixer speed, gradually add the confectioners' sugar and whip for another minute at high speed. Fold in the cookies. (Makes 2 cups.)
For the buttercream: Place the egg whites, sugar and salt in a stand mixer bowl and set the bowl over a pan of simmering water. Whisk until the mixture is warm to the touch and all the sugar has dissolved. Attach the bowl to the mixer and whisk until soft peaks form, 8 to 10 minutes. Add the butter, a few tablespoons at a time, then whisk in the vanilla. Switch to the paddle attachment and continue mixing at low speed until the buttercream becomes smooth, another minute or two. (Makes 5 cups.)
To assemble the cake: Place one cake layer on a cake board and pipe a border of buttercream along the circumference (to act as a pool for the filling). Fill the center with the cookies-and-cream filling. Top with the second cake layer and frost the entire cake with the buttercream.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.