Preheat the oven to 350F. Spray 10 inch round or 9x9 baking pan with non-stick spray. Set aside.

In a large nonreactive mixing bowl, whisk together the flour, baking powder, baking soda, salt and sugars until well mixed. With a pastry blender cut in the butter until it resembles small peas. (I use a food processor)

Reserve scant cup of the mixture in another bowl for the cake topping;set aside. Transfer the remaining mixture to a piece of wax paper.

In the same large bowl, whisk together eggs, buttermilk and vanilla. Stir in the crumb mixture from the wax paper. Pour into prepared pie plate or baking pan.

Fold the chopped nuts and cinnamon into the reserved crumb mixture and sprinkle over the top of the batter. Bake 25 to 30 minutes or until the top is nicely browned and a toothpick inserted into the center comes out clean. Best served warm. Keeps well - stays moist. I have also added some blueberries before the topping.