Sprinkle chicken breasts with sea salt and pepper. Cook bacon until crisp, remove and set aside. Do not discard grease. Brown chicken in the bacon grease for 3 to 5 minutes per side. Place chicken in a 9″ x 13″ casserole dish or pan.
In a small bowl, mix the mustard, honey, mayonnaise and dried onion flakes.
Spread Honey Mustard over each piece of chicken, then layer with mushrooms, crumbled bacon, and shredded cheese.
Bake in a 350° oven for 30 minutes, or until cheese is melted and chicken is done.