1 lb. fresh, unblemished mushrooms, about 14 to 24 depending on size
2 tsp. olive oil
Salt to taste
Freshly ground pepper, to taste
3 tsp. lemon juice
1/4 lb. fresh spinach in bulk or 1/4 of a 10 oz. bag of pkgd. spinach
1/2 tbsp. butter
1/4 c. finely chopped onions
2 tbsp. heavy cream
1/8 tsp. freshly grated nutmeg
1 sm. egg, lightly beaten
3 tbsp. finely chopped prosciutto or other ham
1 tbsp. freshly grated Parmesan cheese

Preheat oven to 400 degrees. If the mushrooms need rinsing, rinse and pat them dry. Remove the stems and reserve the caps and stems. Finely chop the stems. There should be about 1/2 to 1 cup. Set aside.

Put the caps in a baking dish and sprinkle with oil, salt, pepper and 2 teaspoons of the lemon juice. Rub to coat all over. Arrange mushrooms stemmed side down and place in the oven. Bake about 5 minutes, no longer. Remove from oven.

Meanwhile, pick over the spinach to remove any tough stems and blemished leaves. Rinse well and drain. Heat butter in a saucepan and add the onions. Cook, stirring, until the onions are wilted. Add the chopped mushroom stems and the remaining 1 teaspoon of lemon juice. Cook briefly, stirring. Add the spinach and cook until the spinach wilts. Cook until most of the liquid evaporates. Add the cream, nutmeg, salt and pepper and stir. Add the egg and cook about 10 seconds, stirring.

Spoon and scrape the mixture into the container of a food processor or electric blender and blend thoroughly. Return mixture to the saucepan and stir in the prosciutto.

Fill the mushroom caps with equal portions of the spinach mixture, smoothing over the tops. Place the mushrooms filled side up on a baking dish. Sprinkle tops with cheese. Bake for 10 to 15 minutes and serve warm. Makes 14 to 24 stuffed mushrooms.