Step 1Remove the kernels from all 5 ears of corn and weigh out 150 grams, saving the rest of the kernels for use later in the recipe. Place the measured kernels in a large bowl under running water and agitate the kernels to remove all hairs and other impurities. Seal the cleaned kernels in a cryovac bag at 100% vacuum with the butter, salt and sugar. Cook sous-vide at 185 degrees Fahrenheit (85 degrees Celsius) for 15 minutes. Remove from heat and set aside to cool.
Step 2Place the corncobs in a pot, add water to just cover and bring to a boil. Reduce to a simmer and cook for 45 minutes. Strain out the cobs and reserve 50 grams of the corn stock, saving the rest for another use.
Step 3In a small saucepan, gently heat the cream until it reduces by half. Measure 20 grams of the reduced cream, saving the rest for another use.
Step 4Juice the remaining corn kernels and, without straining, reserve 100 grams of the juice. In a bowl set over a pot of simmering water, cook the juice, stirring constantly to avoid scorching, until it begins to thicken to a pudding consistency, approximately 10 minutes. Add in the reduced cream and set the mixture aside to cool.
Step 5Combine the cooled cream mixture with the cooked corn kernels and puree in a blender, thinning as necessary with the measured corn stock to achieve the desired consistency. Pass the puree through a chinois and season with salt to taste. Chill before serving in demitasse cups.