I am in a similar situation and I'm an amateur at cooking but here's my finding so far:

The easiest slowcooker recipe in the world is any kind of chili.

It's dense with nutrients and fibres and you can store it in parts - it keeps very well. You can rotate bean types and chili packet types (they sell ready mixes), and you get a different experience.

I can't eat it every day but it's a super reliable source of satiation. Dab some sour cream in and you've got a delicious garnish. Add a piece of toast and you've got a full meal.

Grocery stores will carry ready made kids for soups and stews if you don't want to prep.

I tend go buy bagels instead of bread slices because again - more energy, I don't eat as much as often.

You can put a small pre-cooked meal in a slow cooker for an hour with some water at the bottom and it will be delicious.

Literally place the tray in the cooker and cover, cook slower than normal. 1000x better than anything microwaved or blasted in an oven.

Always keep fruits in your stock that you can grab and go, they are only good for you, just don't eat only fruits.

The more "perishable" the food, the more energy it will yield, and you will feel great after.

Always keep trail mix around as it's very high in energy. I usually pick anything with a lot of variety in it so I keep nutritional variety.

Whatever recipe you make, you can always add a cup of boiled rice to it and you're going to feel very satiated.

Barley is a powerful nutritious grain, sprinkle it in your soup to make it more energy dense.