Wearing kitchen gloves, remove stems and seeds from jalapeno peppers. Coarsely chop the peppers with a knife or pulse in a food processor in batches.

Coarsely chop the cranberries, also using the food processor for efficiency.

Combine peppers, cranberries, sugar, vinegar, and 1 cup of water in a large pan no smaller than 6- to 8-quarts.

Bring to a boil, gently stirring occasionally. Watch closely as it can boil over.

Boil the mixture at a rolling boil for 5 minutes.

In a small saucepan, stir together powdered pectin and additional water. Bring to a boil and boil for 1 minute.

Stir the cooked pectin mixture into the cranberry mixture.

Bring the combined mixture to a boil again and boil for 1 full minute.

Remove from heat and skim off any foam that may appear.

Fill jars with hot jelly mixture, wipe rims clean, and seal the lids with jar rings.