For Cinnamon Sugar: Combine sugar and cinnamon; set aside until ready to use.
For Coffee Cake Muffins: Combine dry ingredients in large bowl; set aside.
Cream butter and sugars in bowl of electric mixer fitted with paddle attachment on medium speed until light and fluffy. Add vanilla and eggs, 1 at a time, mixing well after each.
Alternately add one-third of the flour mixture and half of the sour cream to butter mixture; mix just until combined and scrape side of bowl as needed. Repeat to use all flour mixture and sour cream. Fold in 9 oz. cookie pieces.
Spray cavities of large muffin pans well. Portion 2-1/2 oz. batter into each of 14 cavities. Sprinkle 1 tsp. Cinnamon Sugar over batter. Repeat layers once.
Bake in 350ºF standard oven 30 to 35 min. or until internal temperature of muffins reaches 195ºF. Cool completely in pan.
When ready to serve, remove muffins from pans. Drizzle each with icing and sprinkle with remaining cookie pieces.