Gram's Recipes - Banana Cake

4 small (or 3 large) ripe bananas
1 cup sugar
1 egg
1/2 cup butter or margarine
2 cups flour
1 tsp baking powder
1/2 tsp salt
1 tsp baking soda
1/2 cup sour milk

Cream butter and sugar, add egg and bananas. Beat until light. Sift flour, baking powder and salt. Dissolve soda in sour milk. Add flour alternating with milk. Pour into well greased pan. Bake at 350 for 40 minutes.