Cream butter and sugar in bowl of electric mixer, then add egg and blend until pale yellow.
Add sour cream (or yogurt), then stir in flour and baking soda.
Add some chocolate chips directly to the batter, reserving about ¼ cup.
Pour half of batter in pan, sprinkle ½ of topping and ½ of remaining chocolate chips. Pour remaining batter on top and sprinkle with remaining topping and chips.
Bake 50-60 minutes, or until done.
Notes
For a crowd, recipe may be doubled and baked in a 9 x 13 pan.