Ingredients
4 ears corn, shucked
4 tablespoons unsalted butter
1 cup minced white onion
Kosher salt and freshly ground pepper
Minced or snipped chives
1 recipe Corn Custard, (optional), for serving
Preparation
Remove kernels from 3 corncobs, then scrape milk from those cobs into a bowl with kernels (you should have about 3 1/2 cups kernels); set aside. Combine scraped cobs and 5 cups water in a medium saucepan. Bring to a boil, then reduce heat and simmer 8 minutes.
Add remaining whole ear corn; simmer 2 minutes more. Strain liquid, discarding cobs and setting aside whole ear. (You should have 4 cups corn broth.) Cut kernels off whole ear and refrigerate in an airtight container until ready to serve.
Return saucepan to medium heat; add butter. When melted and foam subsides, add onion, season with salt, and cook until translucent, about 3 minutes. Stir in broth and reserved corn kernels and cob milk from bowl. Bring to a boil, then reduce heat to medium-low and simmer, partially covered, until corn is tender and sweet, about 10 minutes. Remove from heat; let cool 10 minutes.
Working in batches, transfer mixture to a blender (a high-speed one, such as Vitamix, works best) and purée until very smooth, 2 to 3 minutes a batch (remove center cap from lid and cover opening with a clean kitchen towel, which allows steam to escape). If desired, strain through a fine-mesh sieve for the silkiest texture. Let cool 15 minutes, then refrigerate in an airtight container until very cold, at least 4 hours and up to 3 days.
When ready to serve, ladle soup into bowls containing corn custard; garnish with chives and reserved chilled corn kernels.
