FRENCH ONION STUFFED CHICKEN CASSEROLE

Ingredients

• 2 tablespoons unsalted butter
• 4 large onions halved and thinly sliced
• Pinch of salt and pepper to season
• 2 teaspoons fresh chopped thyme divided
• 2 tablespoons white wine, sherry or balsamic vinegar (OPTIONAL)
• 2 cloves garlic minced
• 1/2 cup beef broth or stock divided
• 1 tablespoon olive oil
• 4 boneless, skinless chicken breasts
• 2 teaspoons garlic powder
• 1 teaspoon ground thyme
• 1 cup shredded gruyere cheese (or mozzarella cheese)
• 4 tablespoons freshly grated parmesan cheese 

Instructions

1. Preheat oven to 400°F (200°C). Lightly grease a 9x12-inch baking dish. Set aside.
2. Melt butter in a large skillet over medium-high heat. Add onions and season with salt, pepper and half of the fresh chopped thyme. Cook for 5-8 minutes until soft.
3. Reduce heat to medium and cook, while stirring occasionally, until onions are caramelized and jammy (about 15 minutes). Pour in 1/4 cup of broth if pan gets too dry, and keep stirring until onions are browned.

This article and recipe adapted from this site