I actually registered to ask this exact question. What I have been doing for four batches now, with good luck so far...
I boil water in a sauce pan, 2 quarts at a time. Cover, cool to room temp, then decant to a new 1 gallon ziploc bag. Seal bag, freeze, repeat. Break into smaller pieces with a hammer before opening bag.
For my last two extract batches I did two boils of 1.5 gal each, so 3 gal of wort and 2 "gallons" of ice.
I was pouring my wort through a strainer to capture the hops and get some oxygen into the wort, straight off the boil, so wort around 200dF.
With 1.5gal of wort and 2 gal of ice in the primary the temp was 32dF at the end of the second boil. With 3 gal of wort on the ice, my 5 gallons of wort was at 65dF by the time I set the brew kettle down, took off my oven mitts and read the thermometer.
Ready to pitch.
Total my wort sat between 70 and 140dF for maybe one entire second.
So far so good. I shall relax and have a homebrew. If I have a trouble with it I'll bump this thread in the future.