Copycat Cracker Barrel Hash Brown Casserole

Ingredients

• 2 tablespoons unsalted butter
• 1 large white onion, finely chopped
• 2 garlic cloves, minced
• 1 can (10-1/2 ounces) condensed cream of chicken soup, undiluted
• 1 cup sour cream
• 1/4 cup grated Parmesan cheese
• 1 teaspoon salt
• 1/2 teaspoon pepper
• 1 package (30 ounces) frozen shredded hash brown potatoes, thawed
• 2 cups shredded sharp cheddar cheese, divided
• Snipped fresh chives, optional