Did extra insulation cause ice crystals in frozen mac & cheese?

I prepared two 9x13" casserole dishes worth of macaroni & cheese (roux based). In terms of the quantity of pasta, I used three pounds. After combining sauce and pasta I baked to try to eliminate moisture in the pasta and to give it that chewy texture.

Then after allowing to cool to below room temperature (I covered it and put it outside in the cold), I proceeded to bag portions. The process was to fill one sandwich-size ziploc bag, wrap the ziploc in saran wrap (squeezing out air in both steps), then wrap in foil, name & date, and put 4-5 units in a 1 gallon freezer bag. Place freezer bag in freezer.

From the very first pull, not four days later, I already had ice crystals. Where did I go wrong? The ice crystals didn't affect the flavor much if at all, is it possible that it's an aesthetic problem, not actually chemical? Could it be the foil usage (for which I received some questions when I explained the storage/packing method)?