I had some trouble with this one a couple of times. The first time I tried to cook it, I threw out the blended orange flesh after getting some of its juice out (I didn't push it through the sieve like the Unofficial Harry Potter Cookbook (the Adams Media one) said), and as a result, the marmalade was runny. This morning, I blended a couple of boiled oranges and add more sugar and a little water to the marmalade and cooked it till got jam-like thick. But after I waited for it to cool, it actually came out crystallized. I guess I'll have to soften it up later and recook it with more water later.

Also, I heard that if you have the marmalade hard like that, it could be used to make cookies. Marmalade cookies, anyone?