Preheat oven to 350. Put the chicken in the casserole dish you will be using for this dish. Cover with foil and bake until cooked to 160 degrees, about 30-35 min. Cool for a few minutes and then shred or chop into bite-sized pieces. Drain any cooking liquid from the casserole dish.
Meanwhile, in a frying pan coated with cooking spray, cook the pepper and onion over medium-low heat until they are golden and soft. I let mine caramelize the entire time the chicken was in the oven. I just left the heat between low and medium and popped into the kitchen to give them a stir every 5-10 min. Cool until warm.
In a large bowl mix the cream cheese, half of the shredded cheddar, and the fajita seasoning. Add the chopped chicken and cooked onion and pepper. Put back into the same casserole dish you cooked the chicken in. Sprinkle on the remaining cheese.
Bake at 350 for 25-30 min until hot and bubbly.
Check out the video of this recipe right above the recipe card!Nutrition: This recipe has 8 servings. I just cut through the cheese and eye up the portions. There are 3.7 NET carbs per serving.Make-Ahead: Prepare through step 3. You can refrigerate the casserole for up to a day or two at this point. I prepped it in the morning and then just popped it in the oven before dinner. If it is chilled before the final bake it will take 30-40 minutes to heat through and get a nice bubbly golden topping.Seasonings: Depending on whether your fajita seasoning includes salt you may need to adjust. Since you have already cooked the chicken you can taste, and go from there!