Preheat the oven to 350° F. In a sauce pan on medium heat, melt the butter into the heavy cream. Once the butter is melted, add the other cheeses and stir until they are melted together. Add in the pepper. Meanwhile, cook the pasta for half of the package’s recommended cooking time. Drain the pasta and add to the cheese mixture. Add the prosciutto and immediately transfer to a baking dish. Bake for about 10-15 minutes, and broil for the last few minutes until the top browns. Serve immediately.