Gather glass canning jars with lids that can hold a total capacity of 3 cups (750ml). Wash the jars and lids with hot soapy water. Dry the jars and lids and set aside.
In a medium-sized pot, combine the chopped peaches, maple syrup, sugar, lemon juice, and pectin crystals. Stir to combine.
Bring the peach mixture to a boil over medium-high heat. Continue to boil until the jam reads 222ºF (105ºC) on a thermometer. Remove the pot from the heat.
Stir in the whisky then carefully ladle the hot jam into the clean jars. Wipe the rims of the jars with a damp cloth to remove any sticky residue, then screw the lids on tightly. Cool the jam completely before storing it in the fridge for up to two weeks.
I leave the skins on my peaches because I like the look of them, and I like the added-fibre, however, feel free to peel your peaches before you begin if you like. You may need an extra peach if you do so.Process the jars of jam if you want. We usually eat our jam so quickly that I don't ever bother.For best results use a thermometer. The jam will reach 220ºF rather quickly, however, it will take longer to climb those last couple of degrees. Be patient and keep your eye on the thermometer.Any stone fruits will work here in place of peaches. Try plums, cherries, apricots, or even a mix.