From gogogogourment.com
Cake:
1 stick butter, softened
3/4 cup sugar
1 teaspoon vanilla
1 egg
2 cups flour
2 teaspoons baking powder
pinch salt
3/4 cup milk
Filling:
3 tablespoons butter, softened
1 tablespoon cinnamon
1/2 cup flour
1/2 cup brown sugar
Topping:
5 tablespoons butter, softened
3/4 cup flour
1/2 cup packed brown sugar
1 tablespoon cinnamon
Preheat oven to 350 degrees.
In the bowl of a mixer, cream together the butter and sugar, scraping down the side occasionally. Add the vanilla and egg, mix in.
In a seperate bowl, mix together the flour, baking powder and salt. Add one half of it to the mixer, and when mostly combined, add the milk. Once the milk is mostly incorporated, add the rest of the flour.
To make filling: in a small bowl, pinch together the softened butter, flour, sugar, and cinnamon until soft crumbs form.
To make topping: add the butter, flour, brown sugar, and cinnamon to a food processor and pulse until coarse crumbs form. You can also use a pastry cutter instead.
Grease 9x9 baking pan. Pour in 1/2 cake batter, and spread to all four corners. Sprinkle the filling over top, then pour in remaining cake batter, and spread carefully across top, disturbing the filling layer as little as possible.
Sprinkle the topping over the top and press lightly so it adheres.
Bake in preheated oven for 45-50 minutes, until a toothpick inserted comes out clean. Cool to warm on wire rack before serving.
