Here’s the recipe: https://www.davidlebovitz.com/chocolatecovere/
It didn’t have any visual or other sensory cues as to what to watch for when heating the butter and brown sugar, so I conferred with my fellow baker (and spouse!), who agreed we shouldn’t feel the grains of the sugar before removing from heat. That added about 20-30 seconds, but maybe I started the timer a smidge too soon: the caramel had just barely showed signs of boiling when I started the timer #ChocolateMatzoCrack (cont’d)