Crisp the bacon: Place the chopped bacon in a large skillet over medium heat. Cook until golden and crisp, 6–8 minutes.
Transfer bacon to a plate and leave 1–2 tablespoons of bacon fat in the pan.
Season the chicken: Pat chicken dry. Toss with 1/2 teaspoon salt, 1/4 teaspoon pepper, and the smoked paprika.
Sear the chicken: Add butter to the skillet. When melted and hot, add the chicken in a single layer.
Sear 3–4 minutes per side, until browned and just cooked through. Remove to the plate with bacon.
Sauté mushrooms: In the same skillet, add mushrooms with a pinch of salt. Cook, stirring occasionally, until they release moisture and turn golden, 5–6 minutes.
Add garlic and deglaze: Stir in garlic for 30 seconds until fragrant.
Pour in chicken broth and scrape up any browned bits from the bottom of the pan.
Make it creamy: Reduce heat to medium-low. Stir in heavy cream, Parmesan, Dijon, thyme, and remaining salt and pepper. Simmer gently 2–3 minutes to thicken.
Combine and finish: Return chicken and bacon to the skillet.
Add spinach if using, and stir until wilted. Simmer 1–2 minutes more, then taste and adjust seasoning. A squeeze of lemon brightens the flavors.
Serve: Garnish with parsley.
Enjoy as is, or serve over cauliflower mash, sautéed zucchini, or steamed green beans.