Preheat the oven to 375 degrees F. Butter a 9-by-12-inch casserole dish and set aside.
Spread the cubed bread on a baking sheet and toast until golden, about 8 minutes. Transfer the bread to the prepared casserole dish.
Meanwhile, heat the butter in a large skillet over medium heat. Add the celery, leeks and some salt and pepper and cook until softened, 5 to 8 minutes. Stir in the creamed corn and sour cream, then lower the heat to medium low. Stir in the eggs 1 at a time.
Pour the creamed corn mixture over the bread. Bake until puffed and cooked through, about 30 minutes.
Recipe courtesy of Nancy Fuller