Heat a large skillet over medium heat then add bacon and cook until crisp. Remove to a paper towel lined plate to drain then pour out all but 1 teaspoon bacon grease and turn heat up to medium-high. Season chicken breasts on both sides with salt and pepper then add to skillet and saute until no longer pink, 3-4 minutes a side. Remove to a plate then tent with foil to keep warm. Melt butter in skillet then add shallots and mushrooms, season with salt and pepper, and then saute until mushrooms are tender, 3-4 minutes. Add spinach then saute until just barely wilted, 1 minute. Add half & half then cook until sauce is thickened, 1 minute, then stir in parmesan cheese. Plate chicken then pour sauce on top and sprinkle with cooked bacon. Serve with pasta or mashed potatoes.