Preheat the oven to 350 degrees Fahrenheit. In a large skillet, add the 1 tablespoon olive oil and 1 diced small onion. Cook until tender. Add in the 2 pounds lean ground beef, cook and crumble until no longer pink.
Add in the 1 teaspoon salt, ¼ teaspoon pepper, ½ teaspoon garlic, and ¼ cup steak sauce. Stir well to combine and remove from heat.
Slice the 12 dinner rolls, in half and lay them in a 9x13-inch baking dish. Lay HALF of the 13 slices American cheese on top of the rolls.
Spread the beef mixture on top of the cheese. Add another layer of cheese and top with the rolls.
Spread the 3 tablespoons melted butter and 1 tablespoon sesame seeds on top of the rolls. Bake for 20-25 minutes or until golden brown.