Heat your butter gently until just melted and then chop your apples into small chunks and mix in.
Add your cold water and then bring to a gentle simmer.
Turn the heat down low and gently simmer until the apples have softened and become mushy. Use your potato masher or a wooden spoon to mash the apples as they cook, they should be ready in about 5-7 minutes. Add a little more water if it all dries up before the apples are soft enough to mash.
Set your apples aside to cool completely.
Meanwhile, mix the rest of the mincemeat ingredients together, except the whisky, in your large mixing bowl.
Once your apples have completely cooled mix them into the rest of your mincemeat ingredients. You may find it easier to mulch them in with your hands.
Finally mix in your whisky.
Take a clean tea towel or similar cloth and drape it over the bowl of mincemeat and leave it to stand for 24 hours in a cool and dry place, out of direct sunlight. This enables the fruit to absorb the liquids.