French Onion Funeral Potatoes with Homemade Crispy Onions

Ingredients

• Frozen cubed hash browns, thawed (32 ounces).
• Unsalted butter, melted (1/4 cup/57g for potatoes).
• Sharp cheddar cheese, shredded (2 cups/226g).
• Sour cream (1 1/2 cups/345g).
• Unsalted butter (1/4 cup/57g for sauce).
• Yellow onion, diced (1 small).
• Garlic, minced (2 teaspoons).
• All-purpose flour (1/4 cup/31g).
• Kosher salt (1 teaspoon).
• Black pepper (1/2 teaspoon).
• Cayenne pepper (1/2 teaspoon).
• Dried mustard (1/2 teaspoon).
• Chicken broth, room temperature (1/2 cup/120g).
• Whole milk, room temperature (1/2 cup/122.5g).
• Yellow onions, thinly sliced (2 large/4 cups).
• Vegetable oil for frying (4 cups).
• Kosher salt for onions (1/2 teaspoon).