Preheat oven to 400 F. Line a small baking sheet with parchment paper. Arrange half of the prosciutto pieces on a baking sheet spread apart so they aren’t touching. Bake prosciutto for 5-7 minutes or until crispy. Keep a close eye on it so the prosciutto doesn’t burn. Remove from the oven and let cool. 

Turn oven temperature down to 350 F. Bring a large stock pot of water to a rolling boil. Cook green beans for 3-4 minutes and transfer into a large bowl filled with ice water. This will stop the cooking process of the beans. Once cooled, drain and transfer beans to a separate large bowl. 

In a large bowl, stir together the soup, milk, black pepper, cheese, 1 cup of crispy fried onions, green beans and crumble half of the crispy prosciutto pieces. Transfer mixture to a large casserole dish. 

Cover the foil and bake for 20 minutes. Remove foil, top with remaining onions and other half of the prosciutto over the beans. Bake for an additional 5-10 minutes or until bubbly and golden brown.