Prepare your water bath canner. Fill the canner with enough water so that once the jars are in the canner, they will be covered by at least one inch of water. Cover and begin to heat over a medium-high heat.

Measure out sugar. Set aside.

Place the raspberries in a large, non reactive kettle. Crush them. Stir in jalapeños. Add ¼ teaspoon of butter, if desired, to reduce foaming.

Sprinkle and stir in the pectin. Cook over high heat until a rolling boil is reached, stirring consistently.

Once a rolling boil is reached, slowly stir in sugar.

Continue to stir until you reach another rolling boil that can not be stirred down. Once a rolling boil is reached, cook for 1 minute, stirring constantly.

Ladle jelly into prepared jelly jars, wipe the rims with a damp cloth, add lids, and tighten rings to fingertip tight. Put into the water bath canner. When the canner has a steady boil going, time and process for 10 minutes.

Once the jelly is done processing, remove the canner from heat and let jars rest in the water for an additional 5 minutes. Finally, remove jars from the canner and allow to cool for 12-24 hours before moving.