Over medium-high heat sauté onions until soft, then add garlic for about 25 seconds.
Add ground beef and brown meat until thoroughly cooked. Season with salt and pepper. Drain and set aside.
Preheat oven to 350 degrees.
Keeping rolls in tact, slice bread in half horizontally. Place bottom portion of rolls in an ungreased baking pan (9x13 works great).
Evenly distribute ground beef mixture over the bottom half of the rolls. (Some of the beef may fall to the sides but let it be messy and just do your best in getting as much meat on the bread as possible.) Using a squeeze bottle, drizzle Thousand Island dressing over ground beef using a zigzag motion. Cover with cheese and place the top portion of the rolls over the meat. Brush the top evenly with melted butter.
Cover with foil and bake for 10 minutes or until cheese is melted. For toastier tops, take foil off and bake uncovered for an additional 3 minutes.
Let cool for a few minutes and then pull or cut apart into 12 individual little cheeseburgers. (A serrated knife makes it easier when cutting through.) Serve warm.