This recipe is my sister-in-law's. When we first noticed that these were not just regular baked beans, we didn't know what to call this dish. And, for whatever reason, someone started calling it "Roadkill Casserole". That doesn't sound very appetizing for a dish at dinnertime. But, because it sounded humorous, the name stuck. But, I refuse to list it that way. It is very yummy.
Preheat oven to 350°F. Spray a 9x13 inch baking dish with cooking spray.
Brown ground beef with onions, in a skillet; drain off grease.
Add in brown sugar, garlic salt, and dry mustard. Mix well. Taste. If it seems too sweet, add in vinegar a little at a time, stir after adding. Taste test, to determine, if it needs any more vinegar, with each addition. Pour all ingredients into prepared baking dish.