Cook pasta according to package instructions in a large pot of boiling salted water until just al dente. Drain well using a colander and set aside.

Heat olive oil in a large skillet over medium-high heat. Add ground beef and let sit undisturbed for 90 seconds, then break apart and cook for 3-5 minutes until browned with no pink remaining. Drain excess fat, leaving 1-2 tablespoons, and transfer beef to a plate.

In the same skillet with the browned bits, add diced onion and cook for 2 minutes, stirring frequently. Add garlic and cook until fragrant, about 1 minute.

Whisk in flour and cook until lightly browned, about 1 minute.

Gradually whisk in beef stock, scraping up any browned bits from the bottom of the skillet. Add marinara sauce and stir in Italian seasoning, dried parsley, oregano, and smoked paprika.

Bring to a boil, then reduce heat and simmer for 6-8 minutes, stirring occasionally, until sauce is reduced and slightly thickened. The sauce should coat the back of a spoon.

Stir in cooked pasta and browned beef, then add heavy cream and stir for 1-2 minutes until heated through. Taste and adjust salt and pepper.

Remove skillet from heat and stir in sour cream until well combined.

Fold in cheddar cheese and stir for 1-2 minutes until completely melted and sauce is smooth and glossy.

Serve immediately, garnished with fresh parsley if desired.