Cook pasta according to package instructions in a large pot of boiling salted water and drain well.
Heat olive oil in a large skillet over medium high heat. Add ground beef and cook until browned, about 3-5 minutes, breaking it with a wooden spoon. Drain excess fat and set aside.
To the same skillet, add diced onion, and cook for 2 minutes, stirring frequently. Add garlic, and cook until fragrant, about 1 minute.
Whisk in flour until lightly browned, for about 1 minute.
Gradually whisk in beef stock and stir to combine. Add marinara sauce and stir in Italian seasoning, dried parsley, oregano, and paprika.
Bring to a boil, reduce heat and simmer, stirring occasionally, until reduced and slightly thickened, about 6-8 minutes.
Stir in cooked pasta, and add back beef.
Next, stir in heavy cream until heated through, about 1-2 minutes. Taste and adjust for salt and pepper.
After that, stir in the sour cream.
Next, fold in the cheddar cheese until melted, about 1-2 minutes.
Serve immediately, garnished with parsley if desired.