Slow Cooker French Onion Soup

Ingredients

3 pounds sweet onions, thinly sliced
3 tablespoons unsalted butter, melted
2 teaspoons brown sugar
Kosher salt and freshly ground black pepper, to taste
6 sprigs fresh thyme
1 bay leaf
6 cups beef stock
2 teaspoons sherry vinegar
1 (12-ounce) French baguette, sliced
1 cup shredded Gruyère cheese
1 cup shredded Asiago cheese

Directions

Place onions into a 6-qt slow cooker.
Stir in butter, brown sugar and 1 teaspoon salt; top with thyme and bay leaf. Cover and cook on high heat for 8-10 hours, or until onions are caramelized and browned.

Stir in beef stock and sherry; season with salt and pepper, to taste. Cover and cook on high heat for 2-3 hours, or until heated through. Remove and discard thyme and bay leaf.

Preheat oven to broil.

Place baguette slices onto a baking sheet. Place into oven and broil until golden brown on both sides, about 1-2 minutes per side; set aside.

Divide soup into ramekins or ovenproof bowls. Place onto a baking sheet. Top with baguette slices to cover the surface of the soup completely; sprinkle with cheeses. Place into oven and broil until golden brown and cheeses have melted; about 2 minutes.