Preheat oven to 400 degrees. Spray a rimmed baking sheet with nonstick cooking spray and place the red and jalapeno peppers on the sheet. Roast for 20 minutes; remove from the oven and flip peppers. Roast 20 more minutes then allow to cool enough that you can touch them. Peel the skin off, cut the peppers in half and discard seeds. Dice into small pieces and set aside.

Butter both sides of each piece of bread using 2 tablespoons of butter. On four slices of bread add 2 slices of pepper jack cheese. On the other four slices add 2 slices of cheddar cheese. Top the pepper jack cheese with even amounts of pepper mixture and top with the cheddar cheese half.

Heat a skillet over medium heat; add the remaining tablespoon of butter and let melt. Place one or two sandwiches in the skillet at a time and grill 2 minutes or until golden brown then flip. Grill an additional 2 minutes. Slice the sandwiches on the diagonal and serve war.