Add hot water and stuffing mix together. Stir until moistened. Set aside.
Remove stems from mushrooms and chop stems. Melt the butter in a skillet on medium heat. Add chopped stems and garlic. Cook and stir for 5 minutes or until tender.
Then add to the stuffing mixture along with the spinach and cheeses. Mix well. Spoon into the mushroom caps. Place them filled side up on a cookie sheet or shallow baking dish.
Bake at 400 degrees for 20 minutes or until mushrooms are tender and filling is heated through.
Notes
The best cheese is more of a personal preference, however, we do love to use shredded mozzarella cheese for this recipe. It melts beautifully allowing it to mix well with the other ingredients creating a delicious creamy bite.