Heat a water bath to 65˚C. (I use the Sansaire immersion circulator, but I know a lot of folks who use and love the Anova.)
Put the chicken breast into a Ziploc freezer bag.
Cook sous vide for 75 minutes.
If you’re going to eat it immediately, remove the bag from the water, remove the chicken from the bag, pat it dry, then sear in a pan over medium heat for 30 seconds per side. Serve immediately.
If you’re saving it for later, chill the chicken—still in the bag—in an ice bath, and then refrigerate.