Preheat the oven to 450°F.
Arrange the chicken breasts on a baking dish lined with parchment paper. Spray the pan with oil and sprinkle some salt and pepper. Bake the chicken for 20 minutes or until cooked.
In the meantime, grease a 2-quart casserole dish
In a large mixing bowl add mayonnaise, sour cream, Dijon mustard, minced garlic, salt, pepper, dried thyme, paprika, cayenne, and ½ cup of the shredded cheddar and mix well until combined thoroughly.
Remove the chicken from the oven after it is cooked thoroughly. Allow the chicken to cool down a bit and cut it into small cubes. Add the chicken cubes to the mixing bowl. Mix it with the mixture until well combined.
Transfer the mixture to the already prepared casserole dish. Sprinkle a half cup of shredded cheddar cheese. Bake until cheese is melted for 5 to 10 minutes.
Sprinkle sliced scallions and bacon pieces on the casserole. Serve now.