Boil the noodles: Bring a large pot of salted water to a boil. Cook egg noodles according to package directions until just tender. Drain and set aside, tossing with a little butter or olive oil to prevent sticking.

Sauté the mushrooms: In a large skillet, heat the olive oil and 1 tablespoon of the butter over medium-high heat. Add mushrooms in an even layer and cook without stirring for 2–3 minutes. Stir and continue cooking until well browned and their liquid evaporates, about 6–8 minutes. Transfer to a plate.

Brown the beef: In the same skillet, add the ground beef. Season with a pinch of salt and pepper. Cook, breaking it up with a spatula, until well browned and no pink remains, about 5–7 minutes. If there’s excess grease, drain off most, leaving about 1 tablespoon in the pan.

Build the flavor base: Add the remaining 1 tablespoon butter and the chopped onion to the beef. Cook until the onion softens and turns translucent, 3–4 minutes. Stir in the garlic and cook 30 seconds, just until fragrant.

Add seasoning and make a roux: Sprinkle the flour, paprika, and Dijon over the mixture. Stir to coat the meat and onions evenly. Cook 1 minute to remove the raw flour taste.

Deglaze and simmer: Slowly pour in the beef broth while stirring, scraping up any browned bits from the skillet. Add Worcestershire and, if using, soy sauce. Return the mushrooms to the pan. Reduce heat to medium-low and let the sauce simmer gently for 5–7 minutes until slightly thickened.

Finish the sauce: Take the skillet off the heat. Stir in the sour cream until the sauce turns smooth and creamy. Taste and season with additional salt and pepper as needed.

Combine and serve: Toss the sauce with the cooked noodles right in the skillet, or serve the stroganoff over a bed of noodles. Sprinkle with chopped parsley for freshness.