Recipe from Cook's Illustrated, July 2011
Notes: During a recent Costco shopping trip, I picked up some vanilla beans from a company called Rodelle. Apparently, Costco's been carrying this item for a few years now. My previous batch, purchased from an online retailer in bulk, had almost turned into twigs in the fridge. I took all of them and steeped them in hot cream to make the ice cream recipe from the current issue of CI.
I actually let the beans sit in the cream for a day in the fridge. When it came time to make the base, I noticed that my custard mixture had not thickened when the thermometer read 180°F. I quickly took it off heat and let it cool. A day or two went by before I could churn it. The whole recipe hinges on freezing the base as quickly as possible so that the ice cream is as creamy as possible. So you have to freezer solid one cup of the mixture, then stir it into the cooled base to "supercool" it, then churn it, then scrape it into a metal pan and freeze that before finally transferring the semi-frozen ice cream into its final container.
While this ice cream was pretty tasty (and smooth), I know it could be better. After some experiments with a cup of ice and water, I determined that my thermometer (a CDN ProAccurate Q2-450) was broken. Not only is it not calibrated properly, it actually reads a higher temperature when I take it from room temperature into ice water. Worse, you can only calibrate it if the measured temperature is between 30 and 41 Fahrenheit. My thermometer has been broken since early 2010 since that's when I noted that my custards weren't thickening. I have no idea why it didn't occur to me to check its calibration in ice and boiling water.
To make this long story short, I bought a new Thermapen directly from the manufacturer. Stores that carry it in this area are either too far (Ontario Gas BBQ) or too expensive (Degrees Kitchen Store) and I couldn't find it on eBay.