Preheat oven to 375 F and prepare two baking sheets with parchment paper.

Remove the stems from mushrooms and set the caps onto the prepared baking sheets. Chop up the mushroom stems small and add to med-low pan with 2 tablespoons butter and garlic. Let cook for 5 minutes until softened, then transfer to a medium mixing bowl.

In the same pan on low heat, add your onions and 2 tablespoons butter and cook until caramelized for about 15-20 minutes stirring occasionally. Add in the red wine and fresh thyme and cook for 5 more minutes until reduced. Remove from the heat and transfer to the mixing bowl with the mushroom stems.

Mix the cream cheese and panko in with the onions, then divide the mixture amongst the mushrooms and top with shredded swiss cheese. Optional : sprinkle more panko and fresh thyme on top before baking.

Bake for 20 minutes until hot and lightly browned. Serve warm!