Creamed Corn Pudding

10-12 large ears of corn, shucked
4 tablespoons butter, divided
2 cups chopped onions
1 cup chopped celery
2 1/2 teaspoons coarse kosher salt, divided
4 large eggs, separated
1/2 cup crème fraîche or sour cream
1/2 teaspoon freshly ground black pepper

Using large holes on box grater, grate enough corn into large measuring
cup to yield 4 generous cups of thick milky pulp. Preheat oven to 425F.
Melt 2 tablespoons butter in heavy large skillet over medium-low heat.
Add onions and celery; sprinkle with ½ teaspoon coarse salt. Sauté
until tender but not brown, 10-12 minutes. Scrape mixture into bowl.
Whisk egg yolks in large bowl 2 minutes. Stir in corn mixture, onion
mixture, crême fraîche, 1/8 teaspoon pepper, and remaining 2 teaspoons
coarse salt. Whisk egg whites in medium bowl until stiff but not dry;
fold into corn batter in 2 additions. Place remaining 2 tablespoons
butter in 10-12 cup cast-iron skillet or baking dish. Transfer to oven
and heat until butter begins to brown, about 4 minutes. Brush butter
over inside of skillet. Add pudding. Bake pudding 15 minutes. Reduce
oven temperature to 350F. Bake pudding until set and golden, about 30
minutes longer. Let stand 5-10 minutes before serving. Makes 10-12
servings.