I preheat my oven to about 375°F, halve jalapeños, remove seeds and veins, then fill each half with cream cheese. I place them on a baking sheet and bake for 25-30 minutes until the peppers are soft, and the cream cheese is bubbling and starting to brown.
While jalapeños are roasting, I cook bacon until crispy. I layer cheddar on two bread slices, Monterey Jack on the other two. Once the roasted jalapeños are done, I slice them into bite-sized pieces, distribute between the cheddar-lined bread slices, and put bacon on the Jack-lined ones. Optionally I add chopped cilantro.
Next, I butter the outside of each bread slice — both the top and bottom. I heat a skillet over medium-low heat, place each sandwich butter-side down, add additional pats of butter on the top sides, then grill both sides until the bread is golden and cheese is melted and gooey.