In a large skillet, heat a tablespoon of oil over medium-high heat. Add 1 pound of ground beef and cook until browned, about 5-7 minutes, breaking it apart with a spatula. Drain excess fat, then add 1 chopped onion and 8 ounces of sliced mushrooms. Sauté until onions are translucent and mushrooms are tender, about 4-5 minutes.

Reduce heat to medium and add 2 tablespoons of butter to the skillet. Once melted, sprinkle in 2 tablespoons of all-purpose flour, stirring to form a roux. Gradually whisk in 2 cups of beef broth, then add 1 cup of milk, ½ cup of sour cream, 1 tablespoon of Dijon mustard, 1 tablespoon of Worcestershire sauce, and 1 teaspoon of paprika. Simmer for 5-7 minutes or until thickened.

In another pot, bring salted water to a boil. Add 8 ounces of egg noodles and cook according to package instructions, usually around 7-10 minutes, until al dente. Drain noodles in a colander and return to the pot to keep warm.

Once sauce has thickened, gently fold in the drained egg noodles until well-coated. Plate Hamburger Stroganoff and garnish with freshly chopped parsley if desired. Serve hot.