01 -
Combine ground beef, onion, mayonnaise, salt, and black pepper in a bowl; mix gently until just combined to avoid tough patties.
02 -
Divide mixture into 24 equal portions and shape each into small, thin patties slightly larger than the rolls to allow for shrinkage during cooking.
03 -
Heat a skillet over medium-high heat and cook patties for 2 minutes per side, spooning off excess grease to prevent sogginess.
04 -
Place bottom halves of rolls on a baking sheet, top each with a slice of cheese, then cooked patties, followed by another slice of cheese to seal in juiciness; cover with roll tops.
05 -
Brush melted butter evenly over the top buns and sprinkle with sesame seeds, pressing lightly so they adhere.
06 -
Bake uncovered in a preheated oven at 350°F (175°C) for 12 to 15 minutes or until cheese is melted and buns are warmed through.
07 -
Remove sliders from oven and serve immediately with preferred condiments and sides, such as dill pickles or baked potato wedges.