Years ago, we fell hard for the bright, velvety simplicity of lemon posset. Now we've used science to prepare this favorite in an array of fruity flavors. Our lemon posset recipe has always been very popular. The rich and silky British dessert is easy to make and calls for only cream, lemon juice, and sugar. The right proportions of ingredients are key to a smooth, luxurious consistency, and for an optimally dense, firm set, we reduce the cream-sugar mixture to 2 cups to evaporate some of the water before adding the juice. A properly set posset also depends on the specific pH of lemon juice, which is about 2.6. To make posset using other types of fruit juices, such as orange, grapefruit, and pineapple, which have a higher pHs, we needed to use citric acid to increase their acidity. Making a citric acid and water solution was the most foolproof way of incorporating the potent powder. Pairing each new fruity flavor of posset with a different topping gave the desserts textural contrast.