24 2 1⁄2 inch diameter portobellini mushrooms (or 4 Large portabello mushrooms), stems chopped, gills removed, caps wiped clean.
4 Tbsp butter
1 large bunch spinach, stemmed and cleaned
1 cup chopped green onions
1 tsp dried oregano
½ tsp ground nutmeg
¼ cup dried breadcrumbs
1 ½ cups parmesan cheese, shredded
1 tsp salt
½ tsp black pepper
4 large eggs
3⁄4 cup whipping cream
Melt butter in a heavy, large skillet over medium-high heat. Add chopped mushroom stems, spinach, green onions, oregano, and nutmeg. Sauté until stems are brown and mixture is dry, about 15 minutes. Add breadcrumbs and sauté another 5 minutes. Transfer to bowl and mix in 1 cup chees, salt and pepper. Cool at least 15 minutes. (Mushrooms and filling can be made 1 day ahead to this point, wrapped separately and refrigerated.) Mix in eggs and cream.
Preheat oven to 375°. Arrange mushroom caps rounded side down on the baking sheets. Spoon filling into mushroom caps and sprinkle with 1/2 cup Parmesan cheese. Bake for approximately 20 minutes, until centers are set.
These mushrooms are a wonderful accompaniment to grilled sausages, or if using the large size, great paired with a salad and foccacia for a light summer meal.