Evenly butter the bread slices on one side each. Heat a pan on medium heat. When the pan is hot, put one slice of bread on the pan, butter side down. Put the cheese on the bread, then sprinkle the red pepper and jalapeño over the cheese evenly. Place the other slice of bread on the cheese, butter side up. Cook slowly, until the bread browns and the cheese melts, about 3 minutes. Carefully flip the sandwich over and cook the other side for about 2 minutes. Remove from pan, cut in half.