Step 1

Preheat oven to 350°.

Step 2

Grease a 9×13 pan and set aside.

Step 3

Take 1 cup of the cake mix and set it aside for the cinnamon streusel topping.

Step 4

In a microwavable safe bowl, melt 1/2 butter. Add remaining cake mix and 1 egg in a small mixing bowl, and stir together with melted butter. Mix until combined. This mixture will seem greasy, but don’t despair, it will cook up nicely. Spread it into the bottom of the pan, and then set aside.

Step 5

In a clean mixing bowl, combine all of the ingredients for the second layer. Whisk together until well combined. Pour on top of the cake layer and set aside.

Step 6

Finally, in a mixing bowl, combine the 1 cup of cake mix that you set aside earlier with sugar, cinnamon, and cold butter cut into cubes. Use two knives or a pastry cutter to cut the butter into the mixture. The mixture should be crumbly.

Step 7

Evenly sprinkle the crumb mixture on top until the cake is covered.

Step 8

Bake for 45-50 minutes until the cake is cooked through and doesn’t jiggle in the middle.

Step 9

Serve warm or cold with whipped cream.