Preheat your oven to 350°F (175°C).

In a large skillet, heat olive oil over medium heat, add ground beef and season with salt and pepper, browning for 5 to 7 minutes.

Add more olive oil if necessary, sauté chopped onions and sliced mushrooms for 5 to 7 minutes, then add minced garlic for the last minute.

Return browned ground beef to the skillet, stir in Worcestershire sauce, soy sauce, Dijon mustard, and beef broth. Simmer for 5 minutes and fold in sour cream.

Cube hamburger buns and scatter them in a greased casserole dish, then pour beef and veggie mixture over the bread layer.

Sprinkle shredded Swiss cheese atop the mixture, and bake for 25 to 30 minutes until cheese is melted and bubbly.

Let sit for a few minutes before serving, garnishing with chopped parsley.