1Preheat oven to 350. Grease and flour a 9x13 inch pan. Make crumb topping first and then set aside.
To make crumb topping: In small bowl, combine flour, sugar and cinnamon. Cut in butter until mixture resembles coarse crumbs.
2In a large bowl, combine flour sugar baking powder and salt. Cut in butter until mixture resembles coarse crumbs (yes, again.) Crack an egg into a measuring cup and then fill with milk to make 1 cup. Stir vanilla into milk and egg. Pour into cake crumb mixture and mix just until moistened. Spread into prepared pan. Sprinkle top with crumb topping.
3Bake for 25-30 minutes, or until toothpick inserted into the center of the cake comes out clean. Allow to cool.