Step 1

Preheat oven to 350

Step 2

Prepare cake mix in large bowl according to directions on box.

Step 3

Spray 9 x 13 pan with non-stick spray.

Step 4

Pour batter into pan.

Step 5

Bake at 350 for 15-20 minutes or until center is just barely set.

Step 6

While cake is baking, prepare crumb topping.

Step 7

In large bowl of electric mixer combine butter, flour, cinnamon, brown sugar and vanilla until all crumbly.

Step 8

Immediately after cake is removed from oven, break crumb topping into marble size pieces with fingers, sprinkling over top.

Step 9

Put back in oven and bake an additional 10-15 minutes (topping will begin to look a less less wet/raw) let cool fully then dust with powdered sugar using a sieve if desired.

Step 10

Cut into squares and serve.