Crunchy Cinnamon Coffee Cake

The Grape Nuts Flakes Cereal makes this coffee cake so tasty and moist!

3 cups Grape Nuts Flakes, lightly crushed
1-1/2 cups firmly packed brown sugar, divided
1-1/2 tsp. ground cinnamon, divided
4 cups all-purpose baking mix (like Bisquick)
1-1/4 cups plus 2 Tbsp. milk, divided
3 eggs
1/4 cup oil
1-1/4 cups powdered sugar

Combine cereal, 1 cup of the brown sugar, and 1 tsp. of the cinnamon; set aside. Mix remaining 1/2 cup brown sugar, the baking mix, 1-1/4 cups of the milk, eggs and oil in separate bowl just until blended. Pour half of the batter into a 13x9-inch baking pan sprayed with cooking spray; sprinkle with half of the cereal mixture. Repeat layers. Bake at 350 degrees for 35 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes. Cut into 24 squares. Beat powdered sugar, remaining 1/2 tsp. cinnamon and remaining 2 Tbsp. milk with wire whisk until well blended. Drizzle over coffee cake. Let stand until set.