Preheat and prep: Heat your oven to 375°F (190°C). Grease a 9x13-inch baking dish or a similar casserole pan.

Cook the noodles: Boil egg noodles in salted water until just shy of al dente (about 1 minute less than package directions). Drain and set aside. Toss with a teaspoon of olive oil to prevent sticking.

Brown the beef: In a large skillet over medium-high heat, add 1 tablespoon olive oil and the ground beef. Season with salt and pepper. Cook, breaking it up, until browned and cooked through, 5–7 minutes. Transfer to a plate and drain excess fat if needed.

Cook the vegetables: In the same skillet, melt 1 tablespoon butter. Add the onion and cook until softened, 3–4 minutes. Add mushrooms and a pinch of salt. Cook, stirring occasionally, until the mushrooms release their liquid and it evaporates, 6–8 minutes. Add garlic and cook 30 seconds.

Make the roux: Push the vegetables to the sides and melt the remaining 2 tablespoons butter in the center. Sprinkle in the flour. Stir and cook the flour-butter paste for 1 minute.

Build the sauce: Slowly whisk in the beef broth until smooth. Add Worcestershire, Dijon, paprika, and thyme. Simmer 3–4 minutes, stirring, until slightly thickened. Taste and adjust salt and pepper.

Finish with sour cream: Reduce heat to low and stir in the sour cream until silky. Do not boil after adding sour cream to prevent curdling.

Combine: Return the cooked beef to the skillet. Add the noodles and half of the cheese. Toss gently to coat everything with the sauce.

Transfer and top: Spread the mixture in the prepared baking dish. Sprinkle the remaining cheese over the top.

Bake: Bake uncovered for 18–22 minutes, until the edges bubble and the top is melted and lightly golden.

Rest and serve: Let the casserole rest 5–10 minutes to set. Garnish with chopped parsley and serve warm.