Ice Cream

Method

1. infuse12 min
   medium-low, steaming not boiling
   milk + half the cream + half the sugar + salt (+ split vanilla pod if using), warmed until sugar dissolves and steam rises — hold it off the boil so no skin forms and no water is lost, which would shift the fat and sugar ratio the whole texture depends on
2. whisk3 min
   off heat
   egg yolks + remaining sugar, until the mixture pales and thickens; the sugar coats the yolk proteins and raises the temperature at which they set, buying you the margin that keeps this from becoming sweet scrambled eggs
3. temper3 min
   thin stream, whisking constantly
   yolk mixture + hot milk added a ladle at a time — dumping it all at once cooks the outside of every yolk droplet instantly and the base goes lumpy, and no amount of straining recovers the lost thickening
4. simmer8 min
   medium-low, 175-180°F, never boiling
   tempered base returned to the pan, stirred across the bottom with a spatula until it coats the back of a spoon and a drawn finger leaves a clean line. Past about 185°F the yolk proteins knot and the custard breaks; the anglaise thickens by hydrating and unfolding those proteins, not by reducing
5. mix2 min
   strained, off heat
   custard strained through a fine sieve + remaining cold cream + vanilla extract (+ corn syrup, which is a large-crystal blocker, + rum, which lowers the freezing point for a softer scoop). The cold cream stops the cooking on contact; the sieve catches the few threads of set yolk that always form at the pan edge
6. rest240 min
   refrigerated, covered, below 40°F
   base chilled thoroughly — this is the step people skip and the one that decides the outcome. A warm base spends its churn time cooling instead of freezing, which means slow ice growth and big crystals; cold base freezes fast and fine. Overnight is better than four hours
7. mix25 min
   ice cream maker, fully frozen bowl
   cold base churned until it holds a soft ribbon and has grown by roughly a quarter in volume. Two things are happening at once: ice crystals are kept microscopic by constant shear, and air is beaten in — without that air it freezes to a solid brick (+ chopped chocolate folded in during the last minute, so it doesn't jam the paddle)
8. store240 min
   freezer, shallow covered container, surface pressed flat
   soft-churned ice cream packed down to drive out large air pockets, covered against the dry freezer air that causes freezer burn, and hardened until scoopable. Straight from the machine it is still soft-serve; the final set is what makes it ice cream