Thinly slice the onions and heat 2 tablespoons of olive oil in a large skillet over medium heat. Add onions and salt, stirring occasionally for 30-40 minutes until golden brown.

In the same skillet, melt 2 tablespoons of butter over low heat. Whisk in 2 tablespoons of flour and cook for 1-2 minutes until it forms a paste. Gradually add 1 cup of heavy cream, stirring continuously until thickened.

Mix in ⅔ of the caramelized onions, salt, pepper, parmesan cheese, and fresh parsley, then turn off the heat once well combined.

Boil a large pot of water with salt. Add 8 ounces of cavatappi macaroni and cook for 7-9 minutes until just under al dente. Drain and return to pot.

Pour the béchamel sauce over the pasta, stirring until well coated.

Preheat oven to 350°F (175°C). Transfer pasta to a greased baking dish, top with remaining caramelized onions and breadcrumbs. Bake for 10-15 minutes until golden and crispy.

Remove from the oven, let cool, and serve hot garnished with fresh parsley.