This. Also you can use coconut flour, as well as nut meals and protein powders. All this stuff works well together. And their calories and carbs differ so you can adjust as needed.

For the fats you can use butter, coconut oil or some other oil. You can also add spices and seasonings (for example caraway seed gives it a bit of the rye bread impression). You can also borrow from the mock danish concept and add a little bit of cream cheese if you want.

You can use this batter to cook like a muffin in the oven, like a pancake on the stovetop, or like a pancake or bowl muffin in the microwave. I must warn you that at least in my kitchen, if I am baking, silicone is the only substance on earth that flax will not stick to like some atomic lovefest, no matter what I do for greasing. For microwaving it was never an issue.

Having the mix made up (if I'm doing that I keep it in the fridge) makes it super convenient. Making something in the mornings so you can eat it the next day (if it's mostly flax that is usually best, the weird thing about flax's taste is that improves with time/refrigeration) is an easy habit, since it's a pretty brief effort.

Best,
PJ