01 - Bring a large pot of salted water to a boil. Cook the macaroni according to package instructions until al dente. Drain well and set aside.
02 - Melt butter in a large pot over medium heat. Add the flour and whisk continuously for 1 to 2 minutes to develop a pale roux.
03 - Gradually pour in whole milk and heavy cream, whisking constantly to prevent lumps. Simmer for 3 to 4 minutes until the base slightly thickens.
04 - Lower heat. Stir in shredded cheddar, Gruyère, and Parmesan, mixing until melted and the soup is silky smooth.
05 - Blend in truffle oil, truffle salt, black pepper, smoked paprika, and nutmeg. Taste and adjust seasoning if needed.
06 - Stir the cooked pasta into the cheese soup. Gently warm for 2 to 3 minutes until the macaroni is heated through.
07 - Ladle the hot soup into bowls. Garnish with a drizzle of truffle oil, toasted panko breadcrumbs, and chopped chives as desired. Serve immediately.