Preheat oven to 350. Spray an 8x8 or 9x9 inch pan with cooking spray.
In mixing bowl or the bowl of a stand mixer, cream the butter and sugar together until light and fluffy. Add egg and mix until combined.
In a separate bowl, combine the flour, baking soda, baking powder, and salt.
Add the dry ingredients to the butter/sugar mixture alternating with the sour cream and vanilla. Scrape the bowl and continue to mix until combined. The mixture will be light and creamy.
In a small bowl combine melted butter, brown sugar and cinnamon for the topping.
Pour batter into greased baking pan and sprinkle with the topping. Bake for 18-22 minutes, until a toothpick inserted in the middle of the cake, comes out clean.
Notes
I used sour cream, but plain greek yogurt would also be delicious and a little bit healthier.Adapted from this recipe.