Juice the apples and allow the juice to sit for 15 minutes so the foam rises to the top. Scrape off as much of the foam as you can so you are left with only juice.
Pour the apple juice into a wide saucepan and bring it to a simmer.Leave it to simmer on medium heat for an hour and a half, stirring occasionally. Scrape off any dregs accumulating not the sides of the pan with a spoon.
After an hour and a half the syrup should have reduced by three quarters and be still runny but sticky. When you stir it with a wooden spoon it should leave a line so you can see the bottom of the pan for at least two seconds.The more you cook the syrup the stickier and more concentrated it will be.