Preheat kitchen appliance to four hundred degrees F. Spray a 2-quart baking dish with oil.
Heat the oil during a massive frypan over medium-high heat, concerning a pair of minutes. Add the meat and also the onions. Cook, stirring to interrupt up the meat, till the meat is suntanned and also the onion is soft, concerning five minutes.
If there ar liquids at all-time low of the frypan, drain the mixture and come back it to the frypan.
Stir within the kosher salt, black pepper, and garlic. Cook, stirring, one a lot of minute.
Turn the warmth off. Stir within the dressing, sugarless cetchup, mustard, and one cup cheese.
Transfer the mixture to the ready baking dish. Sprinkle with the remaining cheese.
Bake till the cheese is liquified and also the casserole is heated through, concerning quarter-hour. Or, if your baking dish is broiler-safe, broil the casserole half dozen inches below the element (not directly below) till cheese is liquified, 1-2 minutes.