Preheat your oven to 400°F (200°C). Arrange the halved Fresno chiles on a baking sheet lined with parchment paper, ensuring they are laid cut-side up.
In a mixing bowl, combine the softened cream cheese, shredded cheddar, Monterey Jack, minced garlic, onion powder, paprika, salt, and black pepper. Mix until smooth and uniformly blended. If desired, fold in the crumbled cooked bacon at this stage.
Spoon the prepared cheese mixture into each pepper half, filling generously and slightly above the edges.
Lightly coat the tops of the stuffed peppers with cooking spray or a modest drizzle of olive oil.
Transfer the tray to the preheated oven and bake for 15 to 18 minutes, or until the peppers have softened and the cheese filling is bubbly and golden brown.
Once out of the oven, sprinkle the tops with chopped chives or green onions and serve the poppers warm.