FOR each serving: Pour 1/4 cup of the milk into upright milk shake blender cup. Add 1-1/2 cups of the ice cream, 1/4 cup of the chocolate syrup, 2 Tbsp. of the base cake, 1/4 tsp. of the cinnamon and 1 Tbsp. of the macadamia nuts; cover. Blend until smooth.
POUR into 16-oz. tall shake glass; top with 1/4 cup of the whipped topping and additional 1 Tbsp. macadamia nuts.