Directions

• First, caramelize onions by adding the grapeseed oil to a large skillet (at least 12 inches), over high heat. Once the oil shimmers, add the onions and sprinkle 1 1/2 tsp Kosher salt evenly over them. For the next 5 minutes, stir the onions frequently, encouraging them to release their moisture. Reduce the heat to medium low and set timer for 75 minutes. Stir onions every 5 minutes for the duration of the cook time, keeping them in one cohesive mass so they don’t lose too much moisture too quickly. If they are drying out, reduce the heat. Once timer is up, onions will be a dark amber color. Pour the sherry into the pan and scrape up all the sticky bits in the pan. Transfer the onion mixture to a 4 qt pot and place over medium heat. Add both broths, thyme, bay leaf (if using), and Worcestershire sauce. Simmer the soup for about 30 minutes. Season to taste with Kosher salt and pepper. Remove the thyme and bay leaf and discard. Combine the grated cheeses in a medium bowl.
  
• Ladle the soup into 4 heat safe bowls, up to an inch from the rim. Float baguette medallions on top, and cover with 1/3-1/2 cup cheese. Repeat this process so each bowl has two layers each bread and cheese. Turn on oven broiler to high. Place soup bowls on a rimmed sheet pan and place in oven, at least 6 inches from broiler heat source. Broil until cheese is golden and bubbly and serve immediately.