Remove stems from mushrooms and place in large mixing bowls. Coat with 1 oz of extra virgin olive oil and salt and pepper to taste. Place on a baking tray with gills up and roast in oven from 15 minutes. Remove allow to slightly cool then turn over to allow juice to drain.
In a sauté pan add 1 oz of olive oil and fresh minced garlic. With medium heat allow for garlic to slightly brown. Add fresh spinach and salt and pepper to taste. Then, begin to stir spinach until it reduces in volume remove from heat drain and cool. Lay spinach out on cutting board and lightly chop.
In a large mixing bowl add half pound of softened butter, salt, pepper, oregano, granulated garlic, basil, parsley and the Japanese bread crumbs. Mix by hand until toughly mixed together. Then form into 1 oz disc.
Using a separate mixing bowl, add in cooked spinach and fontina cheese mix together. Then place 1 to 2 oz of the spinach fontina mixture into each mushroom cap. Top with the gratin butter mix, sprinkle with paprika . At this point either keep cold until future use or bake in oven at 350 until golden brown.