I'm several years post-op, so you should probably amend this if your surgery was recent.
I mix 5-grain oatmeal, granola, Total cereal, and some dried cherries (low glycemic index). I add some water about 3/4 up the cereal and nuke it. Then I cover it with plain yogurt and add two scoops of whey protein and stir.
Yield: Breakfast cereal with 55 grams of protein