Place the first 4 ingredients in a bowl to combine.
Line a cookie sheet with foil and brush lightly with olive oil.
Place the mushrooms stem side down on the cookie sheet, brush the tops with olive oil and bake for 10-15 minutes depending on how big your mushroom is. Discard any excess liquid that is on the cookie sheet.
Turn over the mushrooms stem side up, cover with 2-3 tablespoons of tomato sauce and 2 tablespoons of shredded cheese.
Bake the mushrooms for an additional 10 minutes or until the cheese is melted.