Heat 2 tablespoons of butter in a large oven-safe skillet over medium heat.

Add 2 large onions (thinly sliced) and cook, stirring occasionally, for 30-40 minutes until deeply caramelized and golden brown. Season with salt and pepper.

While onions cook, pat 6 boneless, skinless chicken thighs dry and season both sides with salt, pepper, and ½ teaspoon of garlic powder.

Transfer caramelized onions to a bowl. Increase heat to medium-high.

Sear chicken in batches for 4-5 minutes per side until browned; return onions after searing.

Add 1 cup of beef broth and ¼ cup of dry white wine (or more broth) to the pan, scraping up any browned bits.

Add 2 sprigs of fresh thyme and bring to a simmer.

Reduce heat to low, cover, and simmer for 15-20 minutes until the chicken is cooked through (internal temperature of 165°F).

Preheat your broiler to high.

Pile the caramelized onions on top of each chicken thigh.

Top each thigh with one slice of Swiss cheese.

Place the skillet under the broiler for 2-3 minutes until the cheese is melted, bubbly, and golden.

Serve immediately, spooning the pan sauce over everything. Pair with cauliflower rice or zucchini noodles.