Line 8-inch cake pan with parchment paper. Sprinkle 1 oz. of the OREO Cookie Pieces over bottom of pan. Set aside. Combine flour, cocoa and salt. Set aside. Melt butter; stir in vanilla. 

Warm whole eggs, yolks and sugar over warm water bath to 110ºF. Place in bowl of electric mixer with whip attachment. Mix on high speed until mixture triples in size and leaves a mark when you run your finger through it. Remove egg mixture from mixer.

Gently fold in dry ingredients in thirds, then fold in the melted butter mixture. Pour batter into prepared baking pan. Sprinkle with remaining 1 oz. OREO Cookie Pieces. Bake in preheated 375ºF standard oven 20 min. or until center springs back when lightly touched.

Place one cake layer on bottom of a 3-inch high by 8-inch diameter metal cake ring. Brush simple syrup over top of cake. Soften ice cream and carefully spread over top of cake. Sprinkle with OREO Cookie Pieces. Gently press cookies into ice cream. Freeze until firm.

Heat water to boiling. Combine chocolate, OREO Base Cake and cookie pieces, cocoa, salt and vanilla in a large bowl. Pour water over mixture and let stand 3 min. 

Transfer mixture to food processor or blender. Blend 20 seconds. Pour into clean bowl. Cool at room temperature. Remove cake from freezer. Remove cake from ring and place on a cake board. Drizzle the OREO ganache around the top edge allowing it to flow down the sides of the ice cream. Pipe 12 rosettes with the whipping cream around the edge of the cake. Place a whole OREO Cookie in each rosette. Keep in freezer until ready to slice and serve.