1Line a 6- or 8-inch round cake pan with foil. Spray with nonstick cooking spray. Break each of the biscuits into 1-inch pieces; set aside.
2In medium bowl, place 1 1/3 cup chocolate chips; set aside. In 1-quart saucepan, heat 2/3 cup whipping cream and 2 tablespoons butter over medium heat, stirring until butter is melted and mixture comes to a boil. Pour cream mixture over chocolate and stir smooth.
3Add biscuit pieces to chocolate mixture, gently fold until all pieces are coated. Spoon into the prepared cake pan. Gently press mixture into pan. Refrigerate cake for 3 hours or until firm.
4Remove cake from cake pan and turn upside down onto a serving plate. Remove foil. In small bowl place remaining 2/3 cup chocolate chips. In 1-quart saucepan, heat remaining 1/3 cup whipping cream and 1 tablespoon butter over medium heat, stirring until butter is melted and mixture comes to a boil. Pour cream mixture over chocolate and stir smooth. Pour the melted chocolate over the cake; frost top and sides using a butter knife or offset spatula. If desired, decorate with melted milk chocolate.