Preheat your oven to 400°F (200°C).
Cut the jalapenos in half lengthwise, remove the seeds, and place them on a baking sheet.
Roast the jalapenos in the oven for 10 minutes, or until they are tender and slightly charred. Remove from the oven and let cool.
In a mixing bowl, combine the softened cream cheese and shredded cheddar cheese. Mix until well combined.
Once the roasted jalapenos have cooled, chop them finely and fold them into the cheese mixture. Add salt to taste.
Heat a skillet or griddle over medium heat and spread butter on one side of each slice of bread.
Place two slices of bread, buttered side down, on the skillet.
Spread half of the cheese and jalapeno mixture on each slice of bread in the skillet.
Top with the remaining pieces of bread, buttered side up.
Cook for about 3-4 minutes, or until the bottom slice is golden brown. Carefully flip the sandwiches and cook the other side for an additional 3-4 minutes, until golden and the cheese is melted.
Remove from the skillet, slice, and serve hot.