Directions
Gather all ingredients. Preheat oven to 425 degrees F (220 degrees C) with rack in center position.
Place French onion soup, beef broth, rice, and sherry vinegar in a 10-inch oven-safe skillet, and stir until evenly combined. Place sliced butter evenly over rice mixture. Cover with aluminum foil.
Bake in the preheated oven for 30 minutes. Remove and discard foil, and continue baking at 425 degrees F )220 degrees C) until rice is cooked through and the majority of the liquid is absorbed, 20 to 25 minutes.
Increase oven temperature to broil with rack about 6 inches from heat source. Sprinkle evenly with Gruyère and mozzarella cheese. Broil until cheese is melted and golden brown and rice crisps up around edges of skillet, about 5 minutes.
Garnish with fresh thyme leaves and serve immediately.
ENJOY!!!
