Preheat your oven to 350°F (175°C).
Boil the macaroni in a pot of salted water until it is al dente, approximately 8 minutes, then drain.
In a sizable skillet, heat the butter over a medium flame until melted. Stir in the garlic and onion, cooking until they become clear and soft.
Stir in the heavy cream, milk, salt, pepper, and paprika. Bring to a simmer.
Gradually add the cheddar, Gruyere, and Parmesan cheeses, stirring constantly until the cheese melts and the sauce is smooth.
Add the drained macaroni to the sauce, stirring to coat.
Place the macaroni and cheese mixture into a baking dish. Sprinkle breadcrumbs evenly over the top.
Cook in an oven preheated to the specified temperature for 20 minutes, or until the surface turns golden brown and starts to bubble.
Garnish with fresh parsley before serving.