Surprise Banana Cake By Anonymous recipe Comments | 0 Favorites | 18 This is an old Seattle recipe. Surprise Banana Cake Ingredients 1 cup white sugar1/2 cup unsalted butter2 eggs4 ripe bananas, mashed2 cups all-purpose flour1 teaspoon baking soda1/2 teaspoon salt1/2 cup chopped walnuts1 teaspoon vanilla extract Instructions 1 Preheat oven to 375 degrees F (190 degrees C). Grease and flour one 9 x 13 inch cake pan. 2 Cream together the butter or margarine and the sugar. 3 Add eggs, bananas, flour, soda, salt, nuts, and vanilla. Mix thoroughly and pour batter into the prepared pan. 4 Bake at 375 degrees F (190 degrees C) for 30 minutes. Cool and frost cake.