Pro Tips: Temper the egg yolks by slowly adding the hot milk mixture while whisking constantly – this prevents scrambling. Never let the custard boil; it's done when it coats the back of a spoon. Chill the custard for at least 4 hours (overnight is better) before churning. For easy drizzling, put the cookie butter in a pastry bag or a zip-top bag with a snipped corner. Let the finished ice cream sit at room temperature for 5-10 minutes before scooping.