French Onion Soup

James Edisto Mitchell was an illustrator and artist.  He studied in Paris at the Academy de la Grande Chaumiere and with modernist artist, Edouard Goerg.  Postward Paris had a lifelong influence on James as an artist and a cook.  Shane Mitchell, James' son, found a recipe for French Onion Soup in his fathers letters.  This recipe was adapted from his father's recipe by Shane.   His father recommends to ask your butcher not to trim or scrape down to the marrowbones: their meat, fat, and connective tissue contribute significant flavor and body to the soup. This recipe serves 6.

Ingredients

For the Stock:

• 3 Large Beef Marrowbones (4½ lb.)
• 2 Large Carrots (12 oz.)
• 2 Medium Celery stalks (3 oz.)
• 1 Large Yellow Onion (14½ oz.), unpeeled, halved
• 2 Garlic cloves, unpeeped, smashed
• 2 Small Dried Hot Chilies, such as Bird, Arbor, or Kashmiri 
• 1 Small bunch Italian Parsley
• 1 Small bunch fresh Thyme
• 2 Bay Leaves
• 1 TB. Black Peppercorns
• 1 TB. Kosher Salt

For the Soup:

• 10 TB. unsalted Butter, divided
• 4 Large Yellow Onions (3½ lb.). peeled, halved lengthwise, and sliced ½ inch thick (yields 11 Cups).
• 1 Teaspoon Sugar
• 1 Fresh Baguette, cut into twelve ½ inch slices
• 2 Garlic cloves, peeled and halved
• 2 Cups coarsely grated Gruyêre Cheese
• 2 Cups coarsely grated Parmesan Cheese
• 1 Cup Dry White Wine
• ¼ Cup Dry Sherry
• Kosher Salt and Freshly Ground Black Pepper

Procedure

The following steps are very detailed.  They are included so that the reader understands the process used by James to make his favorite French Onion Soup.

1. Make the stock: preheat oven to 400°F.  Line a large rimmed baking sheet with aluminium foil, place the bones on it, transfer to the oven, and roast until the bones are sizzling and browned and most of the fat has rendered, about 1 hour. 
2. In a large stockpot, add the bones (reserving the pan drippings) and the rest of the stock ingredients.  Cover with 1 gallon cold water, then place over high heat and bring to a boil.  Skim and discard any form that forms on the surface, then lower the heat to maintain a strong simmer.  Cook, uncovered until the liquid has reduced by half, about 2½ hours.
3. Remove the stock from the heat and set aside to cool slightly.  Line a large mesh strainer with cheesecloth and place it over a large heatproof bowl.  Strain the stock, discarding the solids, and let it rest for 10 minutes. Skim and discard and grease that collects on surface.  Measure 8 cups of the stock and reserve any extra for later. 
4. Make the soup.  In a large pot or deep skillet over medium heat, add 8 tablespoons of butter and 2 tablespoons of of the reserved beef drippings.  When the foam begins to subside, add onions and sugar, and season lightly with salt and pepper.  Cook stirring frequently, until the onions have entirely wilted 8-10 minutes, then lower the heat to medium-low and cook, stirring frequently, until they turn soft and golden brown but have not yet completely broken down, 60-70 minutes.  Turn off the heat, then cover to keep the onions warm as you finish the soup.
5. Spread the remaining butter on both sides of the baguette slices.  In a heavy skillet over medium-high heat, toast the bread on both sides until crispy and browned, 8-10 minutes.  Rub each slice all over with the cut side of a garlic clove, the set the toast aside.
6. In a large bow, combine the cheeses and set aside.
7. Preheat the broiler and place an oven rack directly below it. Meanwhile, wash out the stock pot and return it to medium-high heat. Add the reserved 8 cups of beef stock, bring to a bowl, then add the white wine and sherry.  Lower the heat to maintain a simmer, and cook just until you can no longer smell the alcohol, 5-7 minutes.  Season to taste with salt and pepper. 
8. Line a large rimmed baking sheet with aluminum foil, and place 6 oven proof soup bowls on it.  Divide the onions between the bowls (about ¼ cup in each), then ladle the hot broth into each bowl to cover the onions. 
9. Cover each bowl with one or two slices of toast (depends upon the size of the soup bowls), then pile them generously with the reserved cheese.  Carefully transfer the bowls to the broiler and cook until the cheese is melted, bubbly, and browned in places, 5-10 minutes.
10. Serve immediately.