1Preheat oven to 375^. Spray a 9x13 inch baking pan. Set aside.
Cream butter and sugar. Add eggs one at a time and beat well. Add mashed bananas and yogurt. Beat well. Combine and beat in the flour, baking powder, soda and salt.
2Stir in nuts and oatmeal. Blend all well. Pour into prepared baking pan.
Bake at 375^ for 30 minutes and then turn oven down to 350^ and bake for another additional 10-15 minutes - test with a tooth pick because all ovens bake differently . Remove from oven and cool completely.
Combine the 2 ingredients in a small bowl and mix until well blended. Place in refrigerator until cake is cooled. Spread on cake . Serve alone of with ice cream. Enjoy!