Preheat oven to 350 degrees. Butter a 9-inch square baking pan. Wash, drain, and dry berries or defrost frozen ones enough to separate. Toss in small amount of flour with blueberries and set aside.

Cream butter, then add sugar and mix well. Add egg and beat until light-colored. Combine molasses and sour cream and add to butter mixture.

Sift flour, soda, ginger, and salt together and add alternately with molasses-sour cream to sugar mixture. Mix only enouth to blend ingredients. Add blueberries, folding them in lightly. Spoon batter into pan. Bake for 40 minutes or until cake pulls away from sides of pan. Serve warm with or without butter.