Set out your cream cheese to soften. Preheat your oven to 400 degrees F. Line a sheet pan with foil. Grease the foil with cooking spray.
Rinse and dry your jalapeños. Starting at the pointy ends, slice them in half the long way, cutting through the middle of the stems as well. (Leave the stems attached so they can be used as handles when serving.)
Use a teaspoon to scrape out the membrane and seeds. (If you want your poppers extra hot, leave two or three seeds inside each half. Or, you can save some seeds to stir into the cream cheese filling.)
In a small mixing bowl, stir your cream cheese to soften it. Stir in your prosciutto cubes.
Add your Parmesan, paprika and garlic powder to a dinner plate. Stir to combine.
Fill your jalapeño halves with the cream cheese mixture, smoothing the surface.
Press each pepper half, cream cheese side down, into the Parmesan mixture.
Place your jalapeños poppers, cheese side up, on your baking pan. Melt your butter on the stove or in the microwave. (I place my butter in a small, microwave-safe bowl, and heat it, covered, in the microwave.)
Spoon the melted butter onto each jalapeño popper.
Bake for 15 minutes, uncovered, or until the tops are golden brown and the peppers are tender.
Notes
Be careful not to touch your face or eyes after cutting the jalapenos, because it will burn. Wash your hands very well after handling them.If you can't find little cubes of prosciutto at your grocery store, ask the deli worker to slice the prosciutto ¼-inch thick. Then, you can cut it into little cubes at home.