Preheat oven to 350 degrees. Coat a 2-qt casserole dish with a small amount of melted butter and set the remainder aside. Combine the breadcrumbs and Italian seasoning in a medium bowl. Pour about half of the breadcrumbs into the bottom of the dish, spreading into an even layer.

Evenly layer about ⅓ of the mushrooms on top of the breadcrumbs. Drizzle with about 2 Tbsp of melted butter then very lightly season with garlic powder, salt and pepper. Just a light dusting will do—there is a bit of salt in the Parmesan cheese.

Sprinkle remaining breadcrumbs over mushrooms then layer ⅓ of the spinach followed by a third of the Parmesan cheese. Distribute ⅓ of the cream cheese by dotting small amounts evenly across the top.

Repeat the process twice more by adding the next layer of mushrooms and pressing firmly to compress. Drizzle with butter then season lightly with salt, pepper and garlic powder. Evenly distribute spinach, Parmesan cheese and cream cheese until all ingredients are used. Press the ingredients down firmly into the dish to compact them. Don’t worry if it comes up slightly higher than the top of the dish; it will cook down in the oven.

Bake 30–35 minutes or until top of the cream cheese is nicely browned and the mushrooms are tender. Let the dish rest for at least 5 minutes—if you have the willpower!