Chocolate Mousse

Method

1. temper6 min
   chocolate + butter melted gently, cooled to warm
   over barely-simmering water or in short microwave bursts, then off the heat until just warm to a finger — the temperature discipline the whole dessert hangs on: too hot scrambles the yolks ahead, too cool and it seizes against the cold cream behind
2. whisk3 min
   yolks + 1 tbsp sugar into the warm chocolate
   beaten in one at a time — the yolks turn the chocolate into something between sauce and custard, the depth the cream-only school never reaches
3. whisk5 min
   whites + salt to soft peaks, remaining sugar rained in
   to glossy medium peaks — and separately, the cold cream + vanilla to soft peaks; two foams, two jobs: the whites are lift, the cream is silk, and neither can do the other's work
4. fold5 min
   whites first in thirds, then cream, swift and unafraid
   a first scoop of whites stirred in carelessly to loosen, then the rest folded in wide strokes, then the cream — the mousse loses a little air with every stroke and all of it with hesitation; done at 'just combined with a few streaks', because the streaks vanish in the chill and overfolding never comes back
5. rest240 min
   portioned into glasses, refrigerated 4+ hours
   set cold — the mousse firms from pourable to spoon-standing as the chocolate re-crystallizes; served with a little softly whipped cream, and eaten the day it wants to be eaten, which is today or tomorrow, not Friday