Cake Ingredients:
2 1/2 C all purpose flour
1 C sugar
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
12 Tablespoons butter (pieces)
3 eggs
1 teaspoon vanilla extract
2/3 C buttermilk
Filling Ingredients:
1 C light brown sugar
1 1/2 Tablespoons cinnamon
Topping Ingredients:
2 sticks cold unsalted butter
2 1/4 C flour
1 1/2 Tablespoons cinnamon
1 3/4 C brown sugar
2 teaspoons vanilla

2 1/2 C all purpose flour 1 C sugar 1/2 teaspoon baking powder 1/2 teaspoon baking soda 1/2 teaspoon salt 12 Tablespoons butter (pieces) 3 eggs 1 teaspoon vanilla extract 2/3 C buttermilk 1 C light brown sugar 1 1/2 Tablespoons cinnamon 2 sticks cold unsalted butter 2 1/4 C flour 1 1/2 Tablespoons cinnamon 1 3/4 C brown sugar 2 teaspoons vanilla

Preheat oven to 350 degrees.
Spray 9x13 pan
Sift flour, sugar, baking soda salt and powder into a mixer
Add butter a few pieces at a time until it crumbles
Add eggs, vanilla and buttermilk and beat until combined
For Filling: Combine 1 C brown sugar with 1 1/2 Tablespoons cinnamon
Pour 1/2 of cake batter in pan and sprinkle filling on top
Pour remaining batter on top. Use a small knife to make swirls
Topping: wisk together flour, cinnamon, sugar and vanilla
Cut in butter until crumbly. Sprinkle over batter
Bake 45-50 minutes