1. Cut a lengthwise slit down one side of each jalapeño to create a pocket, leaving the stem intact. Using a paring knife or a small spoon, carefully scrape the inside to remove at least some of the seeds in order to make room for the filling.
2. Combine the cream cheese, Monterey Jack, bacon, and 1/2 teaspoon of the salt in a small bowl. Place the mixture in a resealable plastic food storage bag or a large piping bag. (If using a food storage bag, cut one corner of the bag to form a hole that’s large enough to allow the bacon pieces to squeeze through.) Squeeze the mixture to the bottom of the bag, and then fill each pepper with as much of the cream cheese mixture as will fit. Press the slit edges of the pepper together to seal. The peppers can be prepared up to this point up to a day in advance and refrigerated, covered, until ready to fry.
3. In a small bowl, combine the 1/2 cup flour, milk, and egg. Place the remaining 3 tablespoons flour, the panko crumbs, and the remaining 1 1/2 teaspoons salt in a shallow bowl or plate, and stir to combine.
4. Preheat the vegetable oil in a deep fryer to 375°F. Line a baking sheet with paper towels.
5. Working in batches, dip the stuffed jalapeños into the milk batter and then roll them in the panko mixture, pressing to coat. As they are breaded, gently place the jalapeños in the fryer and cook until golden brown, 3 to 4 minutes. Transfer the poppers to the prepared baking sheet to drain briefly. Then place them on a serving
plate and sprinkle lightly with salt. Allow the poppers to cool slightly before serving.
Note: When shopping for the peppers, try to select large jalapeños that are unwaxed and ungreased—any shiny coating will prevent the batter from adhering to the peppers.