Sprinkle and rub the chicken breasts with seasoning salt.
Cover and refrigerate for 30 minutes.
Cook bacon in a large skillet until crisp - crumble it.
In a small bowl, mix the mustard, honey, mayo and onion.
Add the crumbled bacon and the mushrooms.
Heat oil in a large skillet over medium heat.
Brown chicken for 3 to 5 minutes per side.
Move chicken to a casserole dish.
Pile topping on each breast and add shredded cheese.
Bake in a 180° oven for 20-25 minutes, or until cheese is melted and chicken is done.