Sautée one onion
Add a few cloves of garlic minced
Add your ground beef
Once meat is cooked add in half a block of cream cheese and a few tbs of heavy cream
Season with 1 tbs of mustard, onion powder, and garlic powder
Add in 1/2 cup of shredded Swiss cheese
Once melted add your meat to your clean mushrooms
Top with more cheese and bake at 425˚ for 10-15 minutes, or until internal temperature reaches 155˚F (for medium)