Quick French Onion Soup in Instant Pot From Paris

Ingredients

• 3 pounds yellow onions, thinly sliced (about 1.36 kg)
• 4 tablespoons unsalted butter (57 g)
• 1 tablespoon olive oil (15 ml)
• 1 teaspoon granulated sugar (4 g)
• 1/2 teaspoon baking soda (2 g)
• 1/2 teaspoon dried thyme (1 g)
• 1/4 teaspoon dried bay leaf (0.5 g)
• 8 cups beef broth (1.9 liters)
• 1/2 cup dry sherry or dry white wine (118 ml)
• Salt and freshly ground black pepper to taste
• 1 baguette, sliced into ½ inch thick rounds
• 4 ounces Gruyere cheese, shredded (about 113 g)
• 2 ounces Parmesan cheese, grated (about 57 g)