Parmesan-Crusted Au Gratin Potatoes and Onion

Ingredients

• 4 pounds russet potatoes , cut into 1/4-inch slices
• salt and ground black pepper to taste
• 6 tablespoons butter
• 6 tablespoons all-purpose flour
• 1.5 cups whole milk
• 1 cup heavy whipping cream
• 2.5 cups shredded mild Cheddar cheese
• 1 cup shredded Asiago cheese
• 1 sweet onion , sliced into rings
• 0.75 cups sliced green onions
• 0.33 cups shaved Parmesan cheese
• 7 butterys round crackers , such as Ritz®
• 2 tablespoons chopped fresh parsley

Instructions

1. 1

   Place potatoes into a large pot and cover with water; add salt and bring to a boil. Reduce heat to medium-low and simmer until just beginning to soften, 15 to 20 minutes; drain.

2. 2

   Melt butter in a saucepan over medium heat; add flour and whisk until the mixture thickens, 1 to 2 minutes. Pour milk and heavy cream into the saucepan; cook and stir until smooth, 2 to 3 minutes. Melt Cheddar and Asiago cheese into the butter mixture; cook while stirring continually until the mixture is smooth and creamy, 1 to 2 minutes. Season the sauce with salt and pepper.

3. 3

   Preheat oven to 400 degrees F (200 degrees C). Butter a 9x13-inch casserole dish.

4. 4

   Layer about half the sliced potatoes into the bottom of the baking dish. Top the potatoes with sweet onion slices and green onions; pour about 1/3 of the cheese sauce over the onions. Arrange the remaining potato slices into the dish; pour remaining cheese sauce over the potatoes. Sprinkle Parmesan cheese and crushed crackers over the top.

5. 5

   Bake in the preheated oven until hot in the center and beginning to brown at the edge, about 30 minutes. Sprinkle parsley over the top of the dish to serve.