Preheat oven to 350 degrees.
Remove stems from mushrooms and discard.
Place mushrooms on a foiled lined or greased baby sheet.
Sprinkle with ½ teaspoon salt and ¼ teaspoon pepper on both sides.
Bake for 15 minutes and set aside.
In a large skillet, melt 1 tablespoon butter and cook pepper and onions until tender.
Season with ½ teaspoon salt and ¼ teaspoon pepper.
Remove from skillet and set aside.
In the same skillet you used for the veggies, melt the remaining tablespoon of butter and cook the meat to your preference.
Add the provolone cheese and stir until completely melted.
Add back the veggies.
Spoon mixture into the mushrooms, top with more cheese if you like.
Bake for 5 minutes or until mushrooms are warm again and cheese is melted well.