Judging by the incredulous, delighted looks on the food editors faces when they swallowed their first spoonful of what is essentially cold, airy, whipped lemonade, this 19th-century dessert deserves a renaissance. The warm, sunny sweetness of basil infuses the accompanying custard sauce.
Add whites to gelatin mixture and beat at high speed until tripled in volume and thick enough to form a wide flat ribbon that holds its shape on top of mixture when beater is lifted, about 5 minutes (longer if using a hand-held mixer). Transfer to a large serving bowl and chill until set, about 3 hours.
04Bring milk, sugar, and a pinch of salt just to a boil in a small saucepan, stirring until sugar has dissolved. Remove from heat and stir in basil. Let steep, covered, 30 minutes.
05Put yolks in a small bowl. Strain milk mixture through a sieve into another bowl, pressing hard on and then discarding basil, and return to saucepan. Whisk about 1/2 cup warm milk mixture into yolks, then whisk into remaining milk in saucepan. Cook over medium-low heat, stirring constantly with a wooden spoon, until custard coats back of spoon and registers 170°F on an instant-read thermometer.
06Transfer custard sauce to a bowl and chill, stirring occasionally, until cold, about 2 hours.
07Spoon snow pudding into glasses or bowls and top with custard sauce.