Tear the slice of bread into small chunks and soak it in the milk for 5 minutes, then mash it with a fork until it is a loose paste.
Mix the ground beef, bread and milk mixture, onion powder, garlic powder, Dijon mustard, eggs, and Worcestershire sauce in a large bowl until well combined.
Form the mixture into oval patties, about ½ inch thick.
Brown the patties in a skillet over medium heat on both sides. Transfer the patties to a dish to keep warm. You'll finish cooking them soon. Leave any fat remaining in the pan.
Add the sliced mushrooms to the skillet and saute until they’re soft, about 6 minutes.
Deglaze the skillet with beef broth, adding Maggi sauce, thyme, and tomato paste to the mix.
Return the patties to the skillet and simmer over medium heat for 8-10 minutes, flipping the patties half way, or until they’re cooked in the middle. They should reach an internal temperature of 165-F.
Scoot the patties to the side, then mix the cornstarch and 2 tablespoons of water in a small bowl. Drizzle the cornstarch slurry into the sauce in the skillet, and bring back to a simmer to thicken. Simmer for 1-2 minutes.
Season the sauce with salt and pepper to taste then serve!
