Potluck Banana Cake Recipe

In a large bowl, cream butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Stir in vanilla. Combine the flour, baking soda and salt; add to creamed mixture alternately with bananas and sour cream, beating well after each addition. Pour into a greased 13x9-in. baking dish. Bake at 350 ° for 35-40 minutes or until a toothpick inserted near the center comes out clean. Cool completely on a wire rack. For frosting, in a small bowl, beat butter and confectioners' sugar until smooth. Dissolve coffee granules in milk; add to butter mixture and beat until smooth. Spread over cake.