Sterilize 8 half-pint canning jars and their lids in simmering water for 10 minutes.

Score peaches with an 'X', blanch in boiling water for 30 seconds, then transfer to an ice bath, peel, and crush to get 4 cups.

Measure out 5.5 cups of granulated sugar and set aside.

In a large pot, mix crushed peaches, lemon juice, and pectin. Stir gently to remove lumps. Optionally, add butter.

Heat mixture over medium-high heat until it reaches a full rolling boil, stirring constantly.

Add all the sugar at once, return to a hard boil and cook for 1 minute until fully dissolved.

Skim off any foam from the surface after boiling.

Ladle hot jam into sterilized jars, leaving 0.25 inches of headspace.

Process jars in a boiling water bath for 10 minutes.

Allow jars to cool for 5 minutes, then let them sit undisturbed for 12-24 hours to set.