If necessary, cook the bacon (see notes section for suggested methods). Once cool, dice the bacon into small pieces.
Preheat the oven to 350 degrees F. Lightly coat a baking sheet with nonstick spray or line with parchment paper. Arrange the peppers on the sheet pan. Set aside.
In a medium bowl, combine the cream cheese, grated cheese, three-quarters of the bacon, green onion, garlic powder, and salt.
Stir to combine the filling.
Spoon the filling into each jalapeño cavity. Arrange the peppers on the prepared baking sheet, filling-side up.
Sprinkle a small amount of panko on top of each jalapeño, then lightly coat the top of the jalapeños with nonstick spray.
Bake until the jalapeños are tender and the breadcrumbs are golden, about 15 to 18 minutes. If the panko isn't browned to your liking when the peppers are soft, switch the oven to broil and broil for 1 minute. Watch VERY CAREFULLY to make sure the breadcrumbs do not burn (don't walk away!). Remove from oven and sprinkle with remaining bacon. Serve hot.
TO STORE. Place cooked and cooled jalapeño poppers in an airtight storage container in the refrigerator for up to 2 days.
TO REHEAT: Rewarm jalapeño poppers on a baking sheet in the oven at 325 degrees F until heated through. In a pinch, you can also reheat them on a microwave-safe plate in the microwave. Note that the poppers will not be as crisp if reheated in the microwave, however.
TO FREEZE: I would not recommend freezing these, as the texture may be negatively impacted once frozen. Frozen jalapeño poppers tend to turn mushy, and the topping will become soggy.
TO MAKE AHEAD: You can stuff the jalapeños a day in advance, store them in the refrigerator, then bake them just before serving. Leave off the bread crumbs until just before baking.