Potato Gratin with Broth and Parmesan | America's Test Kitchen

Ingredients

• 2 large cloves garlic , peeled and smashed
• 1 tablespoon unsalted butter , softened
• 2 1/4 cups low-sodium chicken broth
• 1/2 teaspoon table salt
• 1/8 teaspoon ground black pepper
• 1 bay leaf
• Pinch cayenne pepper (optional)
• 2 pounds all-purpose potatoes , peeled and sliced 1/8-inch thick or less
• 1/4 cup Parmigiano-Reggiano , grated