Preheat the oven to 425°F and line a baking sheet with parchment paper.
Brush the jalapeños with olive oil and place them on the baking sheet. Roast for about 15 minutes, or until slightly charred. Remove and let cool.
In a medium bowl, mix together the cream cheese, garlic salt, pepper, and onion powder until smooth.
Roughly chop the roasted jalapeños and fold them into the cream cheese mixture.
Butter one side of each slice of bread.
On the unbuttered side of two slices, spread half of the cream cheese mixture. Top each with 3 slices of bacon and ½ cup cheddar cheese. Place the remaining bread slices on top, buttered side facing out.
Heat a skillet over medium heat. Cook each sandwich for 3-5 minutes per side, or until the bread is golden brown and the cheese is fully melted.
Serve immediately.