Ricotta-Portabella Stuffed Tomatoes

Ingredients

• 2 tablespoons unsalted butter, divided
• 1/2 cup finely diced yellow onion (this is about half of an onion)
• 4 ounces (about a handful) baby portabella mushrooms, finely chopped
• 1/4 cup dry white wine (I used a Sauvignon Blanc)
• 1/4 teaspoon garlic powder*
• 1/2 teaspoon Italian seasonings (mixture of basil, oregano, thyme, rosemary, etc.)
• 4 tablespoons of chopped fresh parsley (this is about half a bunch); ( you can substitute 2 tbsp dried parsley)
• 1 cup ricotta cheese
• 1/2 cup shredded mozzarella cheese
• 1/2 cup shredded Parmesan cheese
• 14-15 large cherry tomatoes (vine-ripened, if possible)