I'm not sure if anyone else is doing this or not but I tried it a couple of months ago and it is now my routine for prepping a starter.
Like many of you (I assume) I had a tea kettle just sitting in the cabinet. I quickly connected the dots after spilling half of my wort trying to pour from the pot. Maybe I'm just challenged, but I firmly believe I'm not the only one.
I add my DME and water to the kettle with the lid off, begin to heat, and stir. I insert my thermometer through the spout to sanitize it and get a good idea of when the boil over will be coming.
*There is a large chance of boil over with this technique so be careful!*
When it gets to about 200F, I reduce the temperature a lot out of fear of boil over. If all else fails, lifting the tea kettle off the flame with an oven mitt will get the foam down. Careful, the steam heats up the handle. I have gotten better at the signs of boil over and my most recent attempt was a complete success with no boil over.
Let simmer roughly 10 minutes and during the last 45 seconds I place the lid on tightly. You should make it right to the end of the 10 minutes when the foam starts rising out the spout.
This is where the technique becomes easier. Place the now almost completely sealed kettle in an ice bath in the sink. I can get my kettle down to temperature in about 5 minutes. During this time I'm usually sanitizing the flask, stopper, and airlock. You could easily place the kettle in the freezer if you wanted.
Once you're at temperature just pull the thermometer and pour from the spout straight into your sanitized flask. Add the yeast and place on your stir plate to cheer the little fellas on to a successful brew.
I have this kettle and I can easily do a 1L starter in it.