Melt butter in a large pot over low heat.
Add thinly sliced onion to a pan of melted butter and oil.
Season with Italian seasoning, salt, and pepper and let them carmelize for 25-30 mins over medium heat (stirring every ten mins)
Season chicken thighs with salt, pepper, garlic powder, and smoked paprika on both sides and set aside.
Once onions have caramelized, add in garlic paste and stir. Be sure to cook for an additional 2-3 minutes
Remove carmelized onions from pan and set aside.
Add in 1-2 teaspoons of olive oil and sear chicken thighs for about 5 minutes on both sides.
Remove from pan and let rest.
Deglaze the pan with broth and heavy cream.
Let the sauce thicken for about 5 mins
Add chicken thighs to the pan, top with onions and a little mozzarella cheese.
Place in a 450-degree oven for 15-20 min or until chicken is fully cooked through
Add more cheese at the 10 min mark and let cook the remaining 10 minutes.