I have been using eggcrate for years and I believe it is the best method available. I use a food processor to cut up a variety of frozen foods, mix it together in a large boil and then let it thaw for about 20 minutes. Once it is nice and soft i use a large flat spatula to press it into the eggcrate, of course i forgot to mention this is done on a piece of parchment paper large enough to fold over onto the top of the eggcrate. Once the crate is full, fold over parchment paper, trim the edges, then insert into large freezer bag. Simple as that.
I have found this to be the most consistent method to feed my tank. I have done it before as frozen flat in a ziplock but the chunks i was breaking off where never the same amount of food so many times i found i was over feeding.