Cheeseburger Casserole

INGREDIENTS

• Olive oil spray for the baking dish
• 2 tablespoons olive oil
• 2 lb. extra lean ground beef
• 1 medium onion, finely chopped (6 oz)
• 2 teaspoons coarse kosher salt(not fine salt)
• 1/4 teaspoon black pepper
• 1 tablespoon minced garlic
• 1/4 cup avocado oil mayonnaise
• 1/4 cup unsweetened ketchup
• 1 tablepsoon mustard
• 1 1/2 cup shredded sharp cheddar, divided (6 oz)

INSTRUCTIONS

• Preheat oven to 400 degrees F. Spray a 2-quart baking dish with olive oil. 
• Heat the olive oil in a large skillet over medium-high heat, about 2 minutes. Add the beef and the onions. Cook, stirring to break up the beef, until the meat is browned and the onion is soft, about 5 minutes. 
• If there are liquids at the bottom of the skillet, drain the mixture and return it to the skillet. 
• Stir in the kosher salt, black pepper, and garlic. Cook, stirring, 1 more minute.
• Turn the heat off. Stir in the mayonnaise, unsweetened ketchup, mustard, and 1 cup cheddar. 
• Transfer the mixture to the prepared baking dish. Sprinkle with the remaining cheese. 
• Bake until the cheese is melted and the casserole is heated through, about 15 minutes. Or, if your baking dish is broiler-safe, broil the casserole 6 inches below the heating element (not directly below) until cheese is melted, 1-2 minutes.