In a mixing bowl, combine the diced jalapeños, shredded cheese, cream cheese, salt, and black pepper. Mix well until all ingredients are evenly combined.
Heat a frying pan or skillet over medium heat.
Spread 1 tablespoon of butter on one side of each slice of bread.
Place 2 slices of bread, buttered side down, in the hot skillet.
Evenly spread the jalapeño cheese mixture on top of the bread in the skillet.
Place the remaining slices of bread on top, buttered side up.
Cook until the bottom is golden brown and the cheese is beginning to melt, about 4-5 minutes.
Carefully flip the sandwiches using a spatula, and cook the other side until golden brown and the cheese is fully melted, about another 4-5 minutes.
Remove the sandwiches from the skillet and let them cool for a minute before slicing in half.
Serve hot and enjoy!