Melt enough butter to cover the bottom of your skillet, and set your bread slices inside. Lay a piece of cheese on each slice of bread, and divide the sauteed onions between half of the bread slices. Once the bread is nice & toasty, add your cooked burger patty & roasted jalapenos on top of the slice with the onions. Top with the other slice of toasty, cheesy bread - and press down with your spatula. Cook for another 30 seconds or so & press the sandwich down with a spatula to 'glue' it together. Serve immediately.