Thinly slice the yellow onions and heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the onions, a pinch of salt, and optional sugar, stirring occasionally for about 30–40 minutes.

In the same skillet, add 4 tablespoons of butter over low heat. Once melted, whisk in 1/4 cup of flour to create a roux and cook for about 2 minutes.

Gradually pour in 2 cups of heavy cream while whisking continuously. Once thickened, mix in ⅔ of the caramelized onions, a pinch of nutmeg, and season with salt and pepper.

In a separate pot, bring a large pot of salted water to a boil. Add 8 ounces of cavatappi macaroni and cook until al dente, about 2 minutes shy of the package instructions.

Return the drained pasta to the pot and pour in the creamy béchamel sauce, mixing well to coat evenly.

Preheat your oven to 350°F (175°C). Transfer the pasta mixture into a greased baking dish, spreading it out evenly.

Top with the remaining caramelized onions and a sprinkle of breadcrumbs mixed with ⅓ cup of grated Parmesan cheese.

Place the baking dish in the preheated oven and bake for 10-15 minutes until golden brown.

Once cooled slightly, serve hot garnished with fresh parsley.