Preheat the Oven: Preheat the oven to 350°F.
Prepare the Jalapeños: Carefully cut each jalapeño in half lengthwise. Use a spoon to remove the seeds and veins from each half.If available, wear gloves while handling the peppers, avoid touching your eyes or nose, and wash your hands thoroughly afterward. Arrange the Peppers: Place the prepared jalapeño halves in a single layer on a rimmed baking sheet and set them aside while preparing the filling.
Brown the Sausage: Cook the pork sausage in a skillet over medium heat, breaking it up as it cooks, until it is fully browned and cooked through.
Add the Cream Cheese: Add the cream cheese to the cooked sausage and stir until the cheese is fully incorporated into the sausage mixture. Continue stirring as needed; it may take some time for the cream cheese to blend completely. Mix in the Parmesan: Add the grated Parmesan cheese to the sausage and cream cheese mixture. Stir until the Parmesan is evenly combined throughout the filling.
Fill the Jalapeños: Spoon the sausage mixture into the prepared jalapeño halves, filling each pepper with the cheesy sausage mixture.
Bake the Poppers: Place the filled jalapeños in the 350°F oven and bake for 20–25 minutes, until the filling is hot and the poppers are golden.
Cool and Serve: Remove the baked jalapeño poppers from the oven and allow them to cool before serving.