Position rack in middle position and preheat oven to 350 degrees.
Remove stems from cleaned mushrooms by grabbing them as close to the cap as possible and gently twisting. Roughly chop removed stems and reserve in a separate bowl, while placing intact caps in a larger non-reactive bowl.
Add olive oil and 3 tablespoons wine to the bowl containing mushroom caps and toss gently to evenly coat. Set aside.
In a large skillet, cook sausage over medium-high heat until thoroughly browned. Break apart all chunks with a spatula or wooden spoon as it cooks. Once browned, drain excess fat before proceeding.
Add chopped mushroom stems and garlic to the pan and cook until mushrooms are soft and start to release liquid. Add fresh sage and remaining wine and scrape up any brown bits of sausage from the bottom of the pan. Simmer for a couple of minutes until excess liquid evaporates.
Remove from heat and add softened cream cheese and freshly grated Parmesan cheese. Stir until thoroughly combined and cheese is completely melted. Season with salt and pepper to taste. Cool slightly.
Add one rounded spoonful of sausage mixture to each marinated mushroom cap and arrange stuffing side up in a 13 x 9” glass baking dish. If desired, sprinkle each stuffed mushroom cap with Panko breadcrumbs, freshly grated Parmesan cheese or a combination of both before baking.
Place glass dish in pre-heated oven on center rack and bake for 30 minutes or until mushrooms are soft and filling is browned on top. For a crispier topping, place baking dish under the broiler for a couple minutes when done cooking. If desired, garnish with chopped fresh parsley before serving.