Hello from Michigan

I'm assuming you're already fit and are trying to gain muscle while reducing your already low body fat to an even lower one? If that's the case then you'll want to do a body recomp. It'll take a while but you'll gain muscle and burn fat. You have to eat at a caloric surplus on lifting days and lift heavy, and eat at maintenance or slightly below on rest/cardio days. Or you could just bulk to a heavier weight and add both muscle and fat and then cut and lose fat while maintaining your muscle. That wouldn't take as long as a recomp but you'd probably enjoy a recomp more. As far as healthy foods that are high in calories it depens on what macro you're trying to fulfill. I'll give a small list for each macro while keeping your allergies in mind.

Protein: Mass Gainers, Chicken, Beef, Tofu, Fish
Carbs: Rice, Whole Grain Bread, Quinoa, Beans, Couscous
Fats: Oils (Olive, Canola, Coconut), Fish (Salmon mostly), Flaxseed, Chia Seeds

There you have it. You can do research on the topic of recomp and come up with a plan that would work best for you. Include these foods into your diet and you'll see plenty of gains.

PS: I'm from Michigan so welcome fellow MI Peep!!