@ready123 Yeah one meal a day is clearly not enough, especially as you're lifting and need MORE macros.
Shakes can be useful. I put protein powder and a shit ton of fruit in mine. 3x bananas, a good chunk of berries, and some soy milk if I haven't run out. You can easily put a bunch of nuts in there. Nuts are high calories, high protein, high fat, and blended into a shake are EXCELLENT for bulking up easily and quickly.
Pumpkin seeds, chia seeds, flaxseeds also excellent. But find flavours you like and whatever's cheap near you. Cashews would be great - gives an even creamier taste and texture. They're super expensive where I am. But nuts and seeds are an excellent option for you for the shake. You can easily get 500 calories into a shake that way with very solid macros also. And you won't feel so full/bloated/whatever the issue is as if you'd eaten it all. - e.g. if eating disorder. Buy in bulk and they work out pretty cheap. Peanuts often the cheapest but if you look online you can often find super cheap options to buy in bulk. Can be a useful tool.
You may wish to try overnight oats also. Throw in nuts and seeds and so on also, and you've got a solid breakfast for the day. Easy to make (just refrigerate overnight of course) and can come up with a ton of different recipes.
Another easy way to sneak different stuff in is pancakes. Into the pancake mixture you can blend nuts and seeds and a bunch of veggies. Iirc I remember a lentil pancake or something also. And you won't really taste them (with some experimentation).
That said, best in general to work towards two meals a day and then three meals a day eventually.
Good luck!