For Chicken Sliders: In a large bowl, add ground chicken, egg, milk, breadcrumbs, mozzarella cheese, onion, zucchini, parsley, salt and pepper. Mix well.
Form sliders in round patties, place a cheese string in each and repeat process for each slider.
Place Sliders on the grill for 6-8 minutes each side, until cooked. Remove from grill.
For Cauliflower Buns: In Air-Fryer, spray a good amount of cooking spray.
In a saucepan, add an inch of water, cauliflower rice, with the lid, steam for 6-8 minutes, until softened; remove from heat and let cool.
Using a clean dishtowel, drain cauliflower rice, and squeeze out as much water as possible.
In a bowl, add steamed cauliflower rice, egg, shredded cheese, parmesan cheese, and parsley. Mix all together, then add garlic and onion powder, salt and pepper. Mix until fully combined.
Shape into small Slider Buns for tops and bottom, in a small dish, add Everything bagel seasoning, and coat top halves only, until fully covered.
Place in Air Fryer for 15 minutes, then flip and air-fry for additional 5 minutes, until cooked and golden brown. Remove from heat, let cool slightly and ready to serve with your sliders.