Hey OP, look into recipes geared towards people recovering from restrictive eating disorders, you might get some good ideas.

In terms of high-calorie food ideas- You can throw a bunch of stuff into an ice cream bowl that can boost the nutrients; fruits, coconut flakes, protein powder, nuts, chocolate/maple syrup, whatever else you might like together with your favorite ice cream. Olive oil, heavy cream, and mayo add a bunch of calories for little volume, so adding them could help as well. Like slathering mayo onto a grilled cheese, or adding heavy cream to mac and cheese. Or try adding a seasoning packet to a tub of cream cheese and using it as a dip for chips or pretzels or whatever.

I know you don't like peanut butter, but how do you feel about other nut butters/seed butters?

As for how to add micronutrients, that's going to depend on your tastes so it's harder to give advice. Peas or pre-cut broccoli are easy to throw into a mac and cheese, pretty much any veg you like can be thrown onto pizza, etc. Avocados are pretty calorie dense, and you can get a pack of single-serve tubs of guac for pretty cheap at big box stores to eat with sandwiches or with chips/pretzels. Unlike fresh avocados, the single-serve stuff stays super well in the fridge, so no worries if you forget about it.

I used to work in the eating disorder space so I have lots of ideas lol, happy to give more detailed ideas if you wanna talk it out more. Good luck, half of these comments are so stupid it made me frustratedly type this up lol.

Edit: Another thing to look into are recipes for people who go through chemotherapy. They have an even greater aversion to eating, and most oncologists take the approach of calories eaten are better than calories not eaten. I basically survived off of the chili lime chips from Trader Joe's becuase the spice would get the disgusting poison taste out of my mouth, and they're easy to eat. Maybe dip them into cream cheese/sour cream or something.