The easiest sugar free recipies I have are from the box of no-sugar-needed pectin! I guess that does not really help, as you would need to go buy the pectin anyhow. But, it's just about as easy as it gets. My mom is diabetic, and I usually make her some fruit spread every year. I never used gelatin before, do you have the link to that? It sounds interesting!
The recipe in the Ball brand "No sugar needed" pectin is great.
5 c crushed blueberrys, 1 c 100% juice (apple, pear or grape) or water, 2 T lemon juice, and 1pkg of no sugar pectin. If you wanted to sweeten it a little you can add up to 3 c sugar. (I use a little raw sugar). Makes 6 8oz. jars. I am making 2 more batches tomorrow before it gets too hot.
I just made some. I used the recipe on the no sugar pectin, but modified it. I think it was 5 c crushed berries, 2T lemon juice, 1 pkg pectin were the directions, plus 1c water or juice. I used 1 c white grape juice concentrate for the liquid. Basically you combine the berries, lemon juice, and liquid in a pot and then slowly stir in the pectin. Bring to a boil and boil hard one minute. Once it was cooked, I added some agave nectar (would have used concentrated fruit sweetener but was out) to sweeten it a bit more. Just put some in, stirred, tasted, etc until it tasted right to me. Still way less sweet than sugary jams. Since agave nectar adn cfs re both syrupy, they don't ruin the consistency.
I did the same thing with raspberries too. Hmmm, this is making me crave toast with jam!