6 slices bacon 12 jalapeño chiles, halved lengthwise with stems left intact, seeds and ribs removed Salt 4 ounces mild cheddar cheese, shredded (1 cup) 4 ounces Monterey Jack cheese, shredded (1 cup) 4 ounces cream cheese, softened 2 scallions, sliced thin 3 tablespoons minced fresh cilantro 2 tablespoons gluten free bread crumbs (optional) 1 large egg yolk 2 teaspoons lime juice
Adjust oven rack to upper-middle position and heat oven to 500 degrees. Set wire rack in rimmed baking sheet. Cook bacon in 12-inch nonstick skillet over medium heat until crispy, 7 to 9 minutes. Transfer to paper towel–lined plate. When bacon is cool enough to handle, chop fine and set aside.
Season jalapeños with salt and place cut side down on wire rack. Bake until just beginning to soften, about 5 minutes. Remove jalapeños from oven and reduce oven temperature to 450 degrees. When cool enough to handle, flip jalapeños cut side up.
Mix cheddar, Monterey Jack, cream cheese, scallions, cilantro, bread crumbs, egg yolk, lime juice, cumin, and bacon together in bowl until thoroughly combined. Divide cheese mixture among jalapeños, pressing into cavities. Bake until jalapeños are tender and filling is lightly browned, 9 to 11 minutes. Let cool for 5 minutes. Serve.
TO MAKE AHEAD: The filled and unbaked jalapeños can be covered and refrigerated for up to 1 day. Add 3 minutes to the baking time.