Slice the onions thinly and heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the onions and stir to coat; cook for 30-40 minutes, stirring occasionally, until they are golden brown and sweet smelling. If desired, add a teaspoon of sugar midway through to enhance caramelization.

Once the onions are caramelized, reduce the heat to medium-low and add 3 tablespoons of butter to the same skillet. Let it melt before whisking in 3 tablespoons of flour until it forms a paste. Gradually pour in 2 cups of heavy cream, whisking continuously for about 5-7 minutes until the sauce thickens and is smooth.

Stir ⅔ of the caramelized onions into the béchamel sauce, mixing well. Season with salt, pepper, a pinch of garlic powder, and a sprinkle of oregano for extra flavor. Allow this mixture to simmer on low heat for about 5 minutes.

In a large pot, bring salted water to a boil and add 12 ounces of cavatappi macaroni. Cook the pasta until just below al dente, about 1-2 minutes less than package instructions, then drain the pasta, reserving a cup of the pasta water.

Return the drained pasta to the pot over low heat. Immediately pour the béchamel sauce over the pasta, stirring to combine thoroughly. If the sauce appears overly thick, gradually add reserved pasta water, one tablespoon at a time, until the desired creamy consistency is achieved.

Transfer the pasta mixture into a greased baking dish, spreading it evenly. Top with the remaining caramelized onions and a generous layer of homemade breadcrumbs. The assembly builds layers of flavor that elevate the dish.

Preheat your oven to 350°F (175°C). Bake the assembled pasta dish uncovered for 10-15 minutes until the top is golden brown and crispy.