3 TBS butter in a large pot on medium heat. Put into pot 2 to 3 TBS minced garlic, 1/2 C diced onions, 1 C diced bell peppers (or any pepper you want), 1 C chopped mushrooms. Season with a shake or four of cayanne pepper, 1 tsp cumin, 1 tsp dried oregano, and salt & pepper and cook until tender (10 min). Reduce heat and add in 2 cups milk, 1.5 C grated cheese, and 1/2 C sour cream. Stir until the cheese is melted. Dump in 2 to 3 cups diced COOKED fajita chicken (or smoked chicken) and stir. Dump in 6 medium seeded and diced tomatoes and stir in.
Take about 3/4 of a 13 oz bag of tortilla chips and crush them up (or an entire 9 oz bag). Take half of those chips and cover the bottom of a 13 x 9 baking dish. Pour half of the chicken and sauce mixture on top and spread it out evenly. Sprinkle some diced green onion of top of this layer if you want. Spread out the rest of the crushed chips on top of this then cover them with the rest of the chicken and sauce mixture. Bake, uncovered, for 30 min at 350 degrees F or until the middle is bubbly. Let it sit for 5 min before digging in with one of those cool scoop spatulas (I like to use my Pampered Chef one). This served 4 adults and 2 young kids with no leftovers - everyone had seconds - but I also served it with no side dishes. Had I had a side of mixed veggies there might have been 1 serving leftover.
1 hour ago