Preheat oven to 400°F.
In a small bowl, whisk together mayonnaise, honey and dijon mustard.
In a large, oven-safe skillet on medium-high, cook bacon until crispy then remove from the pan.
Reserve 1 tablespoon of the bacon grease in the pan, and add sliced mushrooms and onion. Cook 5-7 minutes or until lightly browned and tender. Transfer to a bowl.
Pound chicken breasts to ¾” thickness and season on both sides with Tonys. Add butter to the skillet and cook chicken breasts in a single layer in the skillet, about 3 minutes on each side. Turn off the heat.
Return the cooked mushrooms and onion on top of the the chicken breasts. Spoon on top ¾ of the honey mustard sauce. Distribute the crumbled bacon and cheese evenly.
Bake uncovered for 10 minutes or until chicken reaches an internal temperature of 165°F. Serve with the remaining honey mustard sauce and garnished with sliced green onion.
