I cannot bear cooked porridge so make chocolate porridge: 40g oats, 20g milled chia seeds, 1 tsp Nesquik chocolate powder, 1 teaspoon cocoa powder, cold almond milk added to the texture I like (quite milky but my dc like it drier), mix and eat. It's yummy and very filling. DS sometimes mixes in a teaspoon of smooth peanut butter.
For my occasionally fussy eater I make banana chocolate ice cream: frozen chopped bananas, generous spoon of peanut butter, generous spoon of cocoa powder and milk, all whizzed together and served in a bowl with toasted flaked almonds on top.
My DD used to need refuelling often (when actively sporty - now teenager so no longer sporty
) and I would pack nut clusters - dark chocolate and peanut butter melted together and mixed with chopped nuts and seeds, dolloped onto lined baking sheets and set in the fridge. At primary school where no nuts are allowed I just used toasted seeds. Also toasted seeds with a bit of paprika or celery salt are a good snack.
Another school snack was macaroons but made with egg whites (from a bottle) and toasted (ground) sunflower seeds and ground rice instead of almonds, with either cocoa powder or vanilla favouring. They are quite sugary and you can cut back a bit on the sugar but they still need a fair whack to get their chewy texture.
When I do baked beans on toast I add a teaspoon of curry paste and halved cherry tomatoes (sometimes a tin of chickpeas) and serve it with naan bread and chopped coriander for variety. Might help to ring the changes some mornings.