Preheat oven to 375˚F.
Season the chicken thighs with salt, pepper, thyme, and paprika.
Heat 2 tablespoons olive oil in a large oven-safe skillet set over medium-high heat.
Add the chicken thighs to the heated oil, skin-side down, and cook for 5 minutes. Flip over the chicken thighs and continue to cook for 5 more minutes. Add more oil, if needed.
Remove chicken thighs from the pan and set them aside.
Return the pan to the burner and add 3 tablespoons of olive oil. Reduce heat to medium-low and stir in the sliced onions. Stir in the sugar; cover with a lid and cook for 15 minutes.
Remove the lid. Give it a stir and continue to cook for about 5 to 10 more minutes, or until the onions are very soft and caramelized. Add the butter, garlic, salt, and pepper, and cook for 2 minutes.
Increase the heat to medium-high and stir in the wine; bring to a boil and cook for 4 minutes, or until half of the liquid is reduced. Stir in the beef broth and cook for 10 more minutes.
Remove from the burner. Add chicken back into the skillet, arranged on top of the onions. Bake for 15 minutes.
Remove from the oven and sprinkle with the cheese. Place back in the oven and cook until cheese is melted; about 3 to 5 more minutes.
Remove from oven. Garnish with parsley and serve.