Pat the chicken thighs dry with a paper towel and place into a large bowl. Season with kosher salt, black pepper, garlic powder, and poultry seasoning.

Drizzle olive oil into a 12-inch nonstick skillet over medium high heat. Place the chicken thighs into the pan and sear on both sides for 5 minutes per side, until golden brown. Remove from the pan and reduce heat to low. Add condensed french onion soup, Worcestershire sauce, and beef broth into the pan to deglaze the pan. Use a wooden spoon or rubber spatula to scrape the bits off of the bottom of the pan, then pour into the crockpot.

Add sliced onions to the bottom of the crockpot. Place chicken on top of the onions, then sprinkle french onion soup mix on top.

Pour the soup/broth mixture and add diced garlic, bay leaves, thyme, and sliced butter on top. Cover with the lid and cook on low heat for 6 hours, until the chicken is tender and falls off of the bone. (you can also cook on high heat for 4 hours, but I recommend low heat for best results)

Remove the chicken along with the juices and onions and add back into a casserole dish or large oven safe skillet Coat with shredded gruyere cheese and broil in the oven for 3-5 minutes, until the cheese melts and becomes golden brown. (You can also add the cheese to the crockpot and continue to cook for an additional hour) Serve with crusty bread and mashed potatoes or white rice for the ultimate comfort meal.