Weigh the apples after you have peeled and cored them. Cut them into wedges.
Melt the sugar in a big heavy pot, until brown caramel. Add the apples, juice of 2 lemons and finely grated ginger. See supplies for measurements.
The sugar will form lumps, but they will dissolve as you boil the jam.
After 5 minutes of boiling, the sugar is now dissolved. Stir to avoid burning the jam.
After 10-12 minutes your jam is done. Almost all the apple wedges have turned into mash and the remaining pieces are translucent. The consistency should be jam like.
Turn off the heat, and let the jam cool for 5 minutes before adding the butter. Stir the jam until the butter has melted.
The butter is now melted and absorbed into the jam.
Put the jam in sterile jars and keep it in the fridge. It will keep for a month, if you haven't eaten it on toast before then.