Cheeseburger Tater Tot Casserole

• Preheat oven to 350°F. Spray a casserole dish with nonstick cooking spray.
• Cook beef and onion in a large skillet over medium heat, occasionally stirring until beef is brown. Drain the excess fat.
• Stir in mustard, ketchup, and relish. Add salt and pepper to taste. Pour mixture into a prepared casserole dish in an even layer.
• Melt butter in a medium saucepan over medium heat.
• Slowly add in the flour and whisk until smooth. Continue to whisk and cook until golden brown.
• Arrange the frozen tater tots in an even layer over the roux (you will have extras).
• Slowly add in the milk, whisking it to be fully incorporated with the roux. Keep whisking until the sauce is bubbly and thick (about 5 minutes). Add salt and pepper.
• Remove from the heat and whisk in 1-1/2 cups of the cheddar cheese until it is fully melted and smooth.
• Pour the roux evenly over the meat mixture.
• Bake in the oven for 35 minutes. Remove from the oven and sprinkle the rest of the cheese onto the tots. Bake for an additional 5 minutes, or until the cheese is melted.
• Garnish with parsley before serving if you'd like!