Butter a 3-quart baking dish; set aside. Heat 1 tablespoon oil in a large skillet over medium heat. Add the onion rings and a sprinkling of salt. Gently saute until crisp-tender. Add the beans to the skillet and sprinkle lightly with kosher salt and a few grinds of black pepper. Remove and cool slightly. Wipe out skillet and add 1 tablespoon olive oil. Heat over medium heat. Add kale. Sprinkle 1 tablespoon water and season lightly with salt. Cook, turning with tongs, until kale is wilted and cooked down, 3 to 5 minutes. Remove and cool.
Scatter the bean mixture in an even layer in the prepared dish. Add bread cubes, tomatoes, and chorizo. Press the liquid from the kale and add to dish. Top with mozzarella.
In a large mixing bowl whisk the eggs well until blended. Whisk in the olive oil and cream until very well blended. Whisk in Parmesan, 1 teaspoon salt, 1/2 teaspoon pepper, and nutmeg. Pour egg mixture over layers in dish. Cover and chill at least 2 hours or overnight.
Remove baking dish from refrigerator and let stand at room temperature for 30 minutes. Preheat oven to 350 degrees F. Uncover dish; bake about 45 minutes or until puffed and golden brown. Remove and cool on a wire rack for 10 minutes before serving.