Preheat oven to 350ºF. In large mixing bowl, combine all of the cake ingredients. In a stand mixer or using a hand mixer, beat on medium speed until everything is well combined and a smooth batter forms. Pour batter into a greased 9-inch baking pan (or divide between two 9" pans, if you don't want to split the cake later).

Bake for 20 to 25 minutes (12 to 15 minutes if you're dividing between the 2 pans) or until a toothpick inserted into the cakecomes out clean. Cool completely, and place in the freezer for ½ hour before assembling.

Cut 6 Oreo cookies in half and set them aside - these will be used as the garnish. Chop remaining cookies into 1/4-inch pieces and set aside.

Make the Oreo whipped cream in 2 batches. In the bowl of a standing mixer fitted with the whip attachment, whip 2 cups of heavy cream on medium-high speed to a soft peak, and then spoon the cream into a large bowl. In the same mixer bowl, whip the remaining 2½ cups of cream, along with the sugar and vanilla, to a soft peak. Fold into the already whipped cream.

Place about 1 cup of whipped cream in a different bowl and refrigerate until ready to decorate the cake. Fold crushed Oreos into the remaining whipped cream.

Remove the cake from the freezer. Slice the layer in half horizontally to create 2 layers, I like using a cake leveling tool to help make two even layers. Place the bottom layer on a serving plate. Spread about 1/3 of Oreo whipped cream onto the bottom layer of the cake. Top with the second cake layer and use the remaining Oreo whipped cream to frost the top and sides of the cake. Chill in the refrigerator for about 2 hours to allow cookies to soften.

Place reserved whipped cream in a pastry bag fitted with a star tip, re-whisking the cream if necessary. Pipe 12 whipped cream rosettes around the perimeter of the cake and garnish with reserved Oreo cookie halves. Serve immediately, or store in the refrigerator until ready to serve.