Step 1: Cook the Egg Noodles : Bring a large pot of salted water to a boil. Add egg noodles and cook until al dente, according to package directions. Drain, toss with a little butter to prevent sticking, and set aside.

Step 2: Brown the Ground Beef : In a large skillet or sauté pan, heat olive oil (if needed) over medium-high heat. Add ground beef and cook until browned and crumbly, about 5–6 minutes. Drain excess fat if necessary and transfer beef to a plate.

Step 3: Sauté the Vegetables : In the same pan, add a little butter if needed. Add the chopped onions and cook for 3–4 minutes until softened. Add the mushrooms and cook until they release their moisture and start to brown — about 5 minutes. Stir in minced garlic and cook for 30 seconds, just until fragrant.

Step 4: Make the Sauce Base : Sprinkle the flour over the mushrooms and stir well to coat evenly. Slowly pour in the beef broth while stirring to avoid lumps. Add Worcestershire sauce, Dijon mustard, and season with salt and pepper. Stir and bring to a gentle simmer — the sauce will thicken as it cooks (about 3–4 minutes).

Step 5: Add the Beef Back :Return the cooked ground beef to the skillet and stir to combine. Reduce heat to low and simmer for another 5 minutes so the flavors meld.

Step 6: Stir in Sour Cream :Turn off the heat (important — sour cream can curdle if overheated). Stir in the sour cream until the sauce turns creamy and smooth. Taste and adjust seasonings as needed.

Step 7: Combine with Egg Noodles : Add the cooked egg noodles directly into the skillet with the sauce. Toss gently until everything is evenly coated. Garnish with chopped parsley and serve immediately.