Lemon posset is a silky, rich British dessert with bright citrus flavor. We found that using just the right proportions of sugar and lemon juice was the key to custard with a smooth, luxurious consistency and a bright enough flavor to balance the richness of the cream. Lemon
zest was essential to making the lemon flavor even more prominent. For a posset with an optimally dense, firm set, we reduced the cream-sugar mixture to 2 cups to evaporate some of the water before adding the lemon juice, which in turn caused the mixture to solidify. Letting the warm mixture rest for 20 minutes before straining and portioning allowed the flavors to meld even more and ensured a silky-smooth consistency. Pairing the dessert with fresh berries for textural contrast helps keep it from feeling overly rich.