Preheat the oven to 400 degrees F.
In a skillet, over medium-high heat, heat olive oil and melt the butter. Add onions, season with salt and pepper, and cook for 12-15 minutes, stirring occasionally until soft and caramelized. If the skillet gets dry, add a splash of water.
Add minced garlic to the onions and cook for 1 minute or until it’s fragrant. Remove from heat.
To an 9x11-inch baking pan, add the chicken and season with thyme, oregano, salt, and pepper. Add ¼ cup of chicken broth to the pan without washing off the seasonings on the chicken.
Top the chicken with the caramelized onions.
Then top with the cheese.
Bake in the oven for 25-30 minutes, or until a kitchen thermometer inserted in the thickest part of the chicken breast registers at least 165°F.
To crisp up the cheese, place under the broiler for a couple of minutes.
Remove from the oven and garnish with fresh chopped parsley if desired and serve.