Preheat the oven to 425 F and butter a 2-quart baking dish.
On a rimmed baking sheet, toss the squash with 2 tablespoons of olive oil and season with ¼ teaspoon of the salt and pepper. Bake for about 25 minutes, or until the squash is just tender. Stir once or twice to avoid sticking. Reduce the oven temperature to 375 F.
In a large skillet over medium heat, warm remaining 2 tablespoons oil until shimmering. Add the shallot, kale and a pinch of salt. Cook until tender, stirring occasionally to ensure even cooking, for about 5 minutes. Fold the cooked squash pieces in with the kale and stir to combine. Turn off the heat and allow to cool for 5 minutes.
Prepare the topping: In a small bowl, whisk together the butter, Uncle Sam cereal and Parmesan cheese. Set aside.
In a small bowl, whisk together the eggs, Parmesan cheese, heavy cream, milk, nutmeg, remaining ¼ teaspoon salt and black pepper. Turn the squash mixture into the prepared baking dish and pour the liquid over the top. Cover with aluminum foil. Bake for 20 minutes, then remove foil and top with Parmesan topping. Bake uncovered for an additional 20 minutes, or until top is crispy and center is set.
Allow to cool and set for 15 minutes before serving. Cover leftovers and refrigerate for up to 3 days.