TOPPING:

1/2 c. firmly packed brown sugar
2 tbsp. (1/4 stick) butter, softened
1 tbsp. all purpose flour
1/2 c. nuts, chopped
1 (12 oz.) pkg. (2 c.) Nestle Toll House semi sweet chocolate mini morsels, divided

CAKE:

2 c. all purpose flour
1 tsp. baking powder
1 tsp. baking soda
1/4 tsp. salt
1 c. granulated sugar
1/2 c. (1 stick) butter, softened
1 tsp. vanilla extract
3 eggs
1 c. sour cream
1 1/2 c. Nestle Toll House semi sweet chocolate mini morsels, reserved from 12 oz. pkg.

TOPPING: In small bowl, mix brown sugar, butter and flour. Stir in nuts and 1/2 cup mini morsels; set aside.

CAKE: Preheat oven to 350 degrees. Grease 13"x9" baking pan. In small bowl, combine flour, baking powder, baking soda and salt; set aside. In large mixer bowl, beat granulated sugar, butter and vanilla extract until creamy. Add eggs, 1 at a time, beating well after each addition. Gradually beat in flour mixture alternately with sour cream. Fold in remaining 1 1/2 cups mini morsels. Spread in pan. Sprinkle Topping evenly over batter. Bake 45 to 50 minutes until wooden toothpick inserted into center comes out clean. Cool; cut into 2" squares.