The Food Lab: Better Home Cooking Through Science

Splash-Proof Thermapen from ThermoWorks is
pricier than most, but it will last forever and it more
than meets all the essential criteria (see here).
Folks often ask me whether it’s worth purchasing
a probe thermometer. You know, the kind that has a
base that remains outside the oven and a probe on
the end of a wire that you shove into your chicken or
roast and leave in the oven as it cooks. Good models
even have an alarm that will tell you when you’ve
reached a particular target temp. Sounds great,
right? No need to poke around in a hot oven.
The problem with these thermometers, however,
is that it is nearly impossible to tell exactly where
you should place the tip of the probe before you
begin roasting. What may seem like it’s going to be
the thickest or coolest part of the chicken breast
when you look at it in its raw state may not end up
being the coolest—i.e., least-cooked—part of the
chicken when it’s done. What this means is that
whether you use a leave-in probe or an instant-read,
you’re going to have to poke around in there when
the chicken is close to done to find the coolest spot.
For that reason, I use a leave-in probe as an early
alarm system only, sticking with my instant-read to
make the final call.