In a large heavy skillet or frying pan over medium-high heat, melt butter. Add all the chopped mushrooms and garlic; saute until the mushrooms are cooked through and brown, approximately 10 minutes. Add cream and boil until the liquid is completely absorbed, approximately 2 minutes. Remove from heat.
Add the crumbled blue cheese and stir until the cheese melts. Mix in the chopped prosciutto and season to taste with salt and pepper. Transfer the mushroom topping to a bowl.
NOTE: Mushroom topping can be made one (1) day ahead, covered, and refrigerated.
Preheat oven to 375 degrees F.
Arrange the bread slices on a large baking sheet. Bake until just golden, approximately 5 minutes; remove from oven.
Mound one (1) generous tablespoon mushroom topping on each slice of toasted bread. Return to oven and bake until topping is heat through, approximately 6 minutes. Remove from oven.
To serve, sprinkle with chopped parsley.
Makes 18 crostini.
* Can substitute gorgonzola cheese.
Crostini with Mushrooms, Prosciutto, and Blue Cheese Recipe: https://whatscookingamerica.net/lindasandberg/appetizers/crostini-mushroombluecheese.htm