French Onion Soup Gelson's

Ingredients

• 3 Tbsp unsalted butter
• 3 lbs large yellow onions, peeled and thinly sliced
• ¾ tsp kosher salt, divided, plus more to taste
• 6 cups beef stock
• 1 cup dry white wine
• 1 Tbsp dry sherry
• 1 Tbsp all-purpose flour
• ½ tsp freshly ground Gelson’s black pepper, plus more to taste
• 1 baguette, cut into ½” slices
• 1 ½ cups grated Gruyère cheese
• Chopped chives, for garnish
• Special equipment: 4 14-oz or 6 9-oz ramekins