While sausage is browning defrost spinach and drain liquid from it.
Place browned sausage, spinach, bread crumbs, seasonings, 1 tsp olive oil, and 1/4 cup cheese in a mixing bowl and stir together
Clean and Remove stems from Mushrooms.
Fill each mushroom cap with filling.
Place in a baking dish and drizzle with a small amount of olive oil. Top with the rest of the shredded cheese and bake for 20 minutes or until cheese is bubbly and mushrooms are softened.
Serve immediately
Notes
If there is extra filling place in an airtight container and refrigerate or freeze for another batch. Or use it to fill Large shell pasta for dinner later in the week.