Prep mushrooms for baking by removing stem. Reserve removed stems for filling, dice finely. With a damp cloth, wipe off the mushrooms. Place on a baking sheet lined with parchment paper and set aside.
In a saute pan, add diced onion and half of the lemon juice. You'll be "water sauteing" with lemon juice. Cook until onions are translucent. Add garlic and chopped mushrooms. Cook until mushrooms have softened.
Add diced tomatoes, basil and oregano. Cook over medium until tomatoes have softened. Remove from heat.
Fill each mushroom with mixture. Top with a generous sprinkle of Brazil Nut Parmesan.
Cook for 9 to 12 minutes. Brazil Nut Parmesan will brown nicely on top and mushrooms will soften. Serve hot!