This is very similar to 'membrillo' but it has a more delicate taste. My grandmother made this every year with the apples from her farm (she also made her own sheep milk cheese…though I helped her many times to stir the milk I, regretfully, cannot remember her cheese recipe)
You just need to follow our apple jam recipe but with more sugar. For each kilo of apples you need 750 gr of sugar and half a lemon. So peel the apples and cut them into cubes. Toss them with the lemon juice so that they do not get brown. Put them in a pan with the sugar and boil for around 40 minutes (first high heat and as soon as it bubbles reduce it to low heat). Stir it often with a wooden spoon.
When the mixture gets brown put it into a tin or in a foil tray. Let it cool down and cover it with the tin top or with the paper of the foil tray ( you can also do this in a plastic container really). If it is properly covered it lasts forever in the fridge. We made ours in September and it is still great in August.