How to Make It
Preheat oven to 350° F. Butter an 8-inch square or another shallow 2-quart baking dish.
Heat 3 tablespoons of the butter in a small skillet over medium heat. Add the onion and ¹/₄ teaspoon each salt and pepper and cook, stirring occasionally, until softened, 8 to 10 minutes.
In a blender, combine the cream, eggs, flour, sugar, 2 cups of the corn, the remaining 3 tablespoons of butter, 1 teaspoon salt, and ¹/₄ teaspoon pepper; blend until smooth. Add the onion and the remaining cup of corn and pulse once, just to combine.
Pour the mixture into the prepared baking dish and bake until set but still slightly wobbly in the center, 50 to 60 minutes. Sprinkle with the chives.