Cook the bacon and prepare the chicken. Preheat oven to 375°F. Heat a large oven-safe skillet over medium heat. Add chopped bacon and cook until crisp, about 5–7 minutes. While the bacon cooks, pat the chicken dry. Combine flour, paprika, and black pepper in a shallow bowl. Lightly season chicken with salt and dredge in the flour mixture, shaking off excess. Transfer bacon to a paper towel-lined plate, leaving about 1 tablespoon bacon fat in the skillet.
Brown the chicken. Add butter to the skillet. Once melted, brown chicken for 3–4 minutes per side. Chicken does not need to be cooked through. Transfer to a plate.
Cook the onions and herbs. Reduce heat to medium-low. Add onion and cook for 8–10 minutes, until soft and golden. Add minced garlic, chopped sage, and cook for 1 minute.
Reduce the cider. Pour in apple cider, scraping up browned bits. Bring to a simmer and cook for 8–10 minutes, until reduced by roughly one-third.
Make the sauce. Whisk in Dijon mustard. Add 1 teaspoon apple cider vinegar and the heavy cream and simmer gently for 2–3 minutes. Taste and season carefully with salt and pepper (taste first as may not need it depending on how salty your bacon was).
Add apples and chicken. Core apples and cut into thick wedges. Nestle chicken into the sauce and arrange apples around the chicken. Sprinkle Gruyère over the top.
Bake. Bake uncovered for 15–20 minutes, until chicken reaches 165°F and the cheese is melted and lightly golden.
Finish and serve. Let rest for 5 minutes. Taste the sauce and add 1 more teaspoon of apple cider vinegar if desired. Top with crispy bacon and fresh herbs. Serve warm.
