Creating your Caramelized Onion and Brie Chicken can be easy if you follow these detailed steps:

1. Preheat the Oven: Begin by preheating your oven to 375°F (190°C).
2. Prepare the Chicken: Season both sides of the chicken breasts with salt and pepper.
3. Sear the Chicken: Heat 2 tablespoons of olive oil in a skillet over medium-high heat. Add the chicken and cook for about 5-6 minutes on each side until golden brown. Remove from the skillet and set aside.
4. Caramelize the Onions: In the same skillet, add the remaining 2 tablespoons of olive oil. Add sliced onions and cook on medium-low heat, stirring frequently for about 15-20 minutes, until they are caramelized and golden brown.
5. Add Balsamic Vinegar: Once the onions are caramelized, add the balsamic vinegar and cook for an additional 2-3 minutes to incorporate flavors.
6. Combine Chicken and Onions: Place the seared chicken breasts in a baking dish. Top each piece with the caramelized onions.
7. Add the Brie: Arrange slices of brie on top of the onions on each chicken breast.
8. Bake: Place the baking dish in the preheated oven and bake for about 20-25 minutes, or until the chicken is cooked through and the brie is melted.
9. Prepare to Serve: Once finished, remove from the oven and let it rest for a few minutes.
10. Garnish: Optionally, sprinkle fresh thyme over the top before serving for an extra pop of flavor.

These steps will guide you in crafting your masterpiece effortlessly, making your kitchen smell divine!