Preheat oven to 425 degrees.
Clean peppers and cut in half or just leave whole and cut off tops, cleaning out seeds and membrane.
Bake for 8 minutes. Let cool.
While peppers are cooling, mix together cooked sausage, cream cheese and Parmesan cheese.
Put mixture in Ziploc bag. Cut off a bit of one corner. Fill cooled peppers with sausage mixture.
Refrigerate for a couple of hours to let the cream cheese mixture get cold.
Bake at 425 degrees for 20 minutes. Serve warm.