This recipe is from Epicurious – Our Favourite French Onion Soup.

I made the broth from scratch. Roasting beef bones with vegetables and

then simmering for a number of hours. Very rich broth.

Our Favorite French Onion Soup From Epicurious

Ingredients
Serves 4 as a main (or 6 as an appetizer)
5 tablespoons unsalted butter, divided
1 tablespoon vegetable oil
3 pounds Vidalia onions (about 4 medium), halved lengthwise,
peeled, and thinly sliced
1 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
1/2 teaspoon granulated sugar
1-1/2 cups dry white wine
6 cups homemade beef broth or store-bought low-sodium beef broth
10 sprigs thyme
2 bay leaves
1 baguette
1 garlic clove, cut in half lengthwise
2 teaspoons sherry, preferably Fino or Manzanilla
4 ounces Gruyère cheese, grated (about 1 cup)
Special equipment:
kitchen twine, six 8-ounce or four 16-ounce oven-safe ramekins or
bowls (optional)
Step 1
In a large Dutch oven or other large pot, melt 3 tablespoons
butter over medium heat. Add the oil and onions; cook onions are
until softened, stirring occasionally, about 15 minutes. Add the
salt, pepper, and sugar; continue to cook, stirring occasionally,
until onions are deep golden brown and caramelized, reducing heat
slightly if onions seem to be browning too quickly, 35 to 45
minutes more.

Step 2
Add wine and raise heat to high. Cook until almost all liquid has
evaporated, 8 to 10 minutes.

Step 3
Tie thyme and bay leaves into a bundle with twine. Add broth and
herb bundle to pot with onions. Bring to a boil, reduce to a
simmer, and cook, uncovered, until broth is thickened and
flavorful, 20 to 30 minutes. Remove from heat and whisk in
remaining 2 tablespoons butter. Taste and adjust seasoning.

Step 4
Heat the broiler. Cut two 1/2-inch baguette slices for every
serving of soup. Place baguette slices on a rimmed baking sheet
and toast in oven until crisp and dry but not browned, about 1
minute per side. Rub one side of each toast with the garlic clove
and set aside.

Step 5
Place ramekins or oven safe bowls on a rimmed baking sheet, add 1/2
teaspoon of sherry to the bottom of each, and ladle soup on top.
Top each serving of soup with two garlic-rubbed toasts. Divide
cheese among the servings, covering the bread and some of the
soup. Carefully transfer baking sheet to oven and broil until
cheese is melted and bubbling, 4 to 8 minutes. (Alternatively, if
using regular soup bowls: Top each garlic-rubbed toast with some
cheese and return to broiler to melt, about 2 minutes more. Divide
sherry and soup among bowls, sprinkle with remaining cheese, and
top each serving with two cheese toasts.)

Do ahead:
Soup can be made up to 3 days ahead (without toasts or cheese) if
refrigerated, or up to 6 months ahead if frozen. Toasts can be
made (without cheese) and kept sealed at room temperature for up
to 3 days.