Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
Slice the jalapenos in half lengthwise and remove the seeds for less heat, if desired. Place the jalapeno halves cut side down on the baking sheet.
Roast the jalapenos in the preheated oven for about 10 minutes, or until they are slightly charred. Once done, remove from the oven and allow to cool slightly.
In a mixing bowl, combine the roasted jalapenos (chopped), cream cheese, shredded cheddar cheese, and a pinch of salt. Mix until well blended.
Spread the butter on one side of each slice of bread.
Heat a frying pan or griddle over medium heat. Place two slices of bread, butter-side down, on the pan.
Spread the jalapeno and cheese mixture evenly on the unbuttered side of the bread in the pan. Top with the remaining two slices of bread, butter-side up.
Cook for about 3-4 minutes, or until the bread is golden brown. Carefully flip the sandwiches and cook for another 3-4 minutes until the cheese is melted and the other side is golden brown.
Remove from the pan, slice, and serve hot.