Preheat the oven to 375º.
Place bread slices in blender or food processor and pulse to coarse breadcrumbs (not to fine).
4 slices white bread
In a medium mixing bowl, combine breadcrumbs, cheeses, Italian seasoning salt, pepper and beaten egg. Set aside.
1/2 cup Parmesan cheese, 1/2 cup Fontina cheese, 1 tbsp Italian seasoning, 1 egg, 1/4 tsp Kosher salt, 1/4 tsp black pepper
Rinse and clean dirt from the mushrooms. Pat dry with a paper towel. Remove stems and place mushroom tops, cap down in a single layer in a shallow baking pan.
16 oz mushrooms
Mince the mushrooms stems (you can also put them in a food processor)
In a small skillet on med-high heat, add 2 tbsp butter. Once butter melt, add minced mushroom stems, onion and 1 minced garlic clove. Sauté garlic for 1 ½-2 minutes. Remove from heat, transfer to a separate bowl and allow to cool for 2-3 minutes.
2 tbsp minced onion, 6 tbsp butter, 2 large garlic cloves
Rinse the skillet, and place back on stove on medium heat, add 4 tbsp butter and 1 minced garlic clove. Saute for 1-2 min. Add red wine and whisk to combine. Allow this sauce to reduce by half. Reduce heat to low and add cream. Whisk to combine.
2 large garlic cloves, 6 tbsp butter, 1 cup red wine, 1/2 cup heavy cream
Combine the cooled mushroom mixture with bread mixture and fold until combined. Using your hands, scoop ball of mixture and place on each mushroom cap. Push on the stuffing so it gets set into the mushroom but keeps a fairly rounded shape. Set caps back onto baking tray.
Spoon the reduced wine sauce into the casserole dish and bake for 8-10 minutes. Broil on low for 2 min.
Remove baking dish from the oven and sprinkle with fresh parsley and Parmesan cheese. Spoon sauce over mushrooms as you serve them.