Step 1

Preheat oven to 350°F. Mix flour, sugars and cinnamon in large bowl. Cut in cold butter with pastry blender or 2 knives until mixture resembles coarse crumbs. Set aside.

Step 2

Beat cake mix, egg, sour cream, melted butter and vanilla in large bowl with electric mixer on medium speed about 1 minute or just until mixed.

Step 3

Spread evenly in greased and floured 13x9-inch baking pan. Sprinkle evenly with topping mixture.

Step 4

Bake 30 to 35 minutes or until cake pulls away from sides of pan. Cool on wire rack. Cut into squares to serve.