Begin by thinly slicing the five onions. In a large skillet, heat 1 tablespoon of olive oil over medium heat and add the onions. Sauté them for 30-40 minutes, stirring occasionally, until they turn a deep golden brown and caramelized. If desired, sprinkle in 1 teaspoon of sugar to enhance sweetness.

Once the onions are caramelized, reduce the heat to low-medium and add 1 tablespoon of flour to the skillet, stirring constantly to create a roux. Gradually whisk in 3 cups of heavy cream, ensuring the mixture is smooth. If it becomes lumpy, add 3 tablespoons of ice-cold water to help it thicken. Mix in ⅔ of the caramelized onions, along with 1 teaspoon of salt, 1 tablespoon of garlic powder, 1 tablespoon of smoked paprika, and ½ teaspoon of nutmeg.

In a large pot, bring salted water to a boil, then add 300 g of cavatappi macaroni. Cook the pasta until just shy of al dente, about 7-8 minutes. Drain the pasta and reserve some cooking water.

In a large bowl, mix the drained cavatappi with the prepared béchamel sauce, stirring until the pasta is fully coated. Transfer this creamy mixture to a baking dish, and top it with the remaining caramelized onions and homemade breadcrumbs.

Preheat your oven to 350°F (175°C) and place the pasta dish inside. Bake for 10-15 minutes, or until the top is golden brown and crispy. Keep an eye on it to prevent burning.

Once removed from the oven, allow the dish to cool for a few minutes. Garnish generously with fresh parsley and serve warm.