Mushrooms Stuffed With Spinach

From "The Best of Czech Cooking". I have not tried yet, but it sounds yummy! I am posting for ZWT 3.

• Ready In: 30 mins
• Serves: 4-6

Ingredients

• 12  large mushrooms
• 1  lb fresh spinach
• 2  slices bacon, diced
• 1  small onion, finely chopped
• 1⁄2 teaspoon marjoram
• 2  egg yolks
•  breadcrumbs (optional)
•  salt & freshly ground black pepper
• 1⁄2 cup  grated gruyere cheese

Directions

1. Wipe mushrooms clean and cut off the stalk ends if they are dirty. Pull the stalks apart from the caps and chop the stalks finely.
2. Clean the spinach and blanch it in boiling salt water for 2 minutes. Remove, squeeze dry, and chop.
3. Preheat the broiler.
4. Fry the bacon in a pan until well done but not crisp. Add the onion and fry until almost golden, stirring occasionally. Add the chopped mushroom stalks and fry for a few more minutes.
5. Take the pot off the stove. Mix in the spinach and marjoram. Mix in the egg yolks. Add some bread crumbs if the mixture needs thickening. Season with salt and pepper.
6. Fill the mushrooms with the stuffing, cover with grated cheese, and broil 10 minutes, or until the cheese is bubbly and golden.