Adjust the number of jalapenos depending on their size. This recipe will stuff 12 large or 24 small peppers.
To hold the peppers upright, I use a foil bread pan and cut X's in the bottom, place upside down, and press the jalapenos into each hole. I can usually get 6 to 8 in each. It makes cleanup easy. Just throw them away after cooking. I also have a jalapeno rack I got at a store, but the foil is way easier and will accommodate various sized jalapenos.