French Onion Stuffed Chicken Casserole

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  2 tbsp Unsalted Butter
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  4 Yellow Onion(440g)
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  1 1 pinch salt (to season)
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  1 1 pinch pepper (to season)
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  2 tsp Thyme, Fresh
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  2 tbsp Wine, White, Dry
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  2 Garlic(6g)
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  0.5 cup Low Sodium Beef Broth
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  1 tbsp Olive oil

  Regular (not extra-virgin) olive oil for high-heat cooking. EVOO for dressings.

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  4 Chicken Breast, Boneless Skinless(1088g)

  Boneless skinless. Buy in bulk and freeze — Costco rotisserie packs work too.

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  2 tsp Garlic powder
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  1 tsp Thyme, Dried
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  1 cup Cheese, Gruyere

  Part-skim mozzarella. Pre-shredded bags are convenient for meal prep.

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  4 tbsp Parmesan Cheese

  Grated Parmesan — the shelf-stable canister is fine for cooking.

Instructions

1. 1Melt the butter in a large skillet over medium-high heat. Add the onions and season with salt, pepper, and half of the fresh thyme. Cook 5–8 minutes until softened, stirring occasionally.
2. 2Reduce heat to medium and continue cooking, stirring occasionally, until the onions are deeply caramelized and jammy, about 15 minutes total. If the pan begins to dry out, add 1/4 cup of the beef broth and keep stirring. Pour in the white wine to deglaze the pan, scraping up browned bits, and cook 1 minute until the liquid reduces slightly. Stir in the fresh garlic and cook 1 minute until fragrant. Remove from heat and let cool slightly.
3. 3Cut each chicken breast horizontally to create a pocket. Season the chicken all over and inside each pocket with salt, pepper, garlic powder, and dried thyme. Spoon 1–2 tablespoons of the caramelized onions into each pocket, then divide the Gruyère and Parmesan between the pockets. Seal each breast closed with toothpicks.
4. 4Transfer the remaining caramelized onions to a 9×12-inch baking dish. Mix in the remaining beef broth and set aside.
5. 5Heat the olive oil in the same skillet over medium-high heat. Sear the stuffed chicken breasts 4 minutes per side over medium-high heat until golden brown on both sides (they will not be fully cooked at this stage).
6. 6Arrange the seared chicken breasts over the caramelized onions in the baking dish. Spoon some of the pan sauce from the dish over each breast and top with the remaining fresh thyme.
7. 7Cover the baking dish with foil and bake at 375°F for 15–20 minutes until the chicken reaches an internal temperature of 165°F in the thickest part.
8. 8Remove toothpicks from the chicken. Divide evenly into 4 airtight containers while hot, spooning the caramelized onions and pan juices over each portion. Cool before refrigerating for meal prep storage.