Cookies – Nuts and raisins don’t stick to cookies after baking

The cookies will set (take on their final texture) about by 20 - 30 minutes out of the oven. Coming directly out of the oven, cookies will absolutely be soft and squishable; which is why you should wait a few minutes before moving them off the baking sheet and onto a cooling rack (you can cheat this time if your cookies are all on a sheet of parchment paper, and you move the parchment paper as a whole).

The cooking technique to make the filling is basically the same as any compote or jam so I would say it would work well for most soft bodied fruit and other jam favourites.

You may have to modify the technique slightly to accommodate for fruit with higher water content to get the same spreadable texture: i.e. simmer the fruit in the sugar water until it starts to break down, strain and reserve the fruit and then either reduce the remaining liquid or only use a fraction of it and recombine with the fruit.