Not 'true' cereal, but tastes alot like it...
4 scoops of vanilla whey, preferablly 0-1 carbs per serving. 12 tablespoons of milled flaxseed as the cereal. Add enough water to give the way a milk consistency. Eat in a bowl with a spoon. Tons of fiber, and protein. Add in some whipping cream for fat.
400 calories from whey (80-100 grams of protein), you could use less, like 2-3 scoops
540 calories from flax (36 grams of fat, you could use less, like 9-10 TBLspoons)
50-100 calories from 1-2 tablespoons whipping cream