Lay two slices of bread butter-side down in the skillet. Top each with one slice of cheese. Divide the tomato and jalapeno between the bread slices and top with remaining cheese.
If your skillet is large enough, lay the remaining bread slices butter-side down into the skillet. This prevents you from having to flip the sandwiches to brown them on both sides. Bad things can sometimes happen when you flip a sandwich! But, if you're a good flipper, put the remaining bread on top of the sandwiches, butter-side out.
Cook until bread is nice and browned. Flip when ready and brown on other side if you aren't cooking the top slices separately. Otherwise, top the sandwiches with the cooked top slices.