Sift together flour, soda, baking powder, and salt; adding ½ cup of flour if at high altitude. Mix sour cream and vanilla together. Alternate adding dry ingredients ad sour cream mixture to creamed mixture.
Spread1/2 batter in greased 9x9 pan. Cover with topping. Cover with rest of batter and another layer of topping.
Bake at 350F for 40 minutes. Test for doneness as it often needs more time.
Recipe by Opsreys Journeys at https://www.ospreysjourneys.com/?p=2882