Using an electric mixer, cream butter and sugar. Add egg and sour cream, mix until blended. Add flour, baking soda & salt; mix on lowest speed just until dry ingredients are incorporated. Spread batter in baking pan and set aside. Prepare topping by combining sugars, flour & cinnamon in a medium bowl. Cut in butter with a pastry cutter or two knives until the mixture is crumbly. Sprinkle half of the topping over the batter. Arrange sliced peaches decoratively over the top. Sprinkle the remaining topping over the peaches. Bake for 35 to 40 minutes or until golden brown. Serve warm.
