My husband found a protein shake made with the following to be pretty tasty and relatively easy to get done: 1 packet vanilla breakfast essentials, 1-2 scoops ice cream, and milk. As he healed, we added a few slices of canned peaches to the mix. Then some toddler's rice flakes. The big day was adding cooked oatmeal (just don't burn out your blender!).
He still starts the day with a protein shake including milk, whey powder (the kind with natural vanilla), and cooked oatmean - now he adds fresh fruit, and sometimes malt. He still to remind himself to eat - so you are not alone in that. Best wishes.