This French Onion Potato Soup Is My Favorite Winter Weekend Project

Name: This French Onion Potato Soup Is My Favorite Winter Weekend Project
Ingredients: 3 pounds yellow onions , sliced 1/2-inch thick; 1 cup water; 2 tablespoons extra-virgin olive oil , divided; 2 teaspoons salt , divided, plus more to taste; 1 teaspoon light brown sugar; 6 cups beef broth , divided; 1 clove garlic , minced; 2 1/4 pounds russet potatoes , peeled and sliced into 1-1/2-inch pieces; 1/4 teaspoon freshly ground black pepper , plus more to taste; 3/4 cup half and half , warmed; 1 teaspoon Worcestershire sauce; 4 to 6 (1-inch-thick) slices baguette; 1 to 1 1/2 cups freshly grated sharp cheddar cheese; Fresh thyme , for serving, optional