Microwave the first three ingredients together in a large bowl for 3 minutes. (I use a large serving bowl so the oatmeal doesn't run over in the microwave. If the oats aren't soft in 3 minutes, cook longer until the desired texture is reached. Some microwaves are stronger than others.) You could also cook this mixture on the stovetop until the desired consistency is reached.

Stir the cocoa powder and sweetener into the oatmeal. Top with a moderate amount of sliced banana and a splash of almond milk if desired. (Sometimes I stir a little almond milk into the oatmeal along with the cooca powder and sweetener if I want it to be thinner or not so dark chocolatey.) Since we're allowed a teaspoon of fat in a THM:E meal, sometimes I add a teaspoon of coconut oil or peanut butter to the oatmeal. Smearing the peanut butter on top of the oatmeal after stirring the cocoa powder in lets you get more noticeable flavor.

Update: I've found that stirring in 2 T. whey protein powder and 1 tsp. refined coconut oil when I add the cocoa powder and sweetener really revs my metabolism! Add a little bit of almond milk if it's too thick.

Another update: I actually prefer collagen over whey protein for less taste. I cook the oatmeal; stir in my salt, sweetener, cocoa powder, and collagen; then top with half a sliced banana. Since I'm allowed 5 grams of added fat in a THM E meal, I like to add a splash of half and half, a few sugar free chocolate chips, or a teaspoon of natural peanut butter to the top of the oatmeal as well.