Pat chicken dry with a paper towel. Season chicken with Herbs de Provence, Salt, and Pepper.
Over medium low heat, add sliced bacon to the skillet and allow bacon to cook slowly until crispy and fat has rendered out - about 10 minutes. Remove bacon bits and set aside.
Increase heat to medium high and add chicken breasts to the pan and sear on both sides until golden brown - about 4 minutes per side. Remove from the pan and set aside.
Add onions to the pan and saute until softened and fragrant, about 3 minutes. Then add diced garlic, mushrooms, and thyme and continue to cook for 5 minutes. Season with salt and pepper.
Add chicken breasts back into the pan and along with white wine or chicken broth. Cover with a lid and cook until chicken breasts are cook thoroughly, about 20 minutes.
Once finished, remove chicken from the pan. Reduce heat to low and add heavy cream and dijon mustard and cook until slightly thickened, about 5 minutes. Then add butter and mix together in the pan until butter has melted. Add chicken breasts back in and sprinkle with the bacon.