Heat oven to 350°F. Grease 13x9-inch pan with shortening or cooking spray. In large bowl, mix sugar, butter and eggs with spoon until combined. Stir in buttermilk, bananas and vanilla until well blended.
Stir in flour, oats, baking soda and salt until well combined. Fold in chocolate chips. Spread batter evenly in pan. Sprinkle nuts evenly over top.
Bake 30 to 35 minutes or until toothpick inserted in center comes out clean. Serve warm or cool.