In a frying pan, saute the prosciutto or ham in the olive oil until crispy; Drain on brown paper or paper towels.
In a large bowl, beat the eggs; Add the Parmigiano-Reggiano, salt and pepper, and basil or parsley; Add the spaghetti and mix well, then stir in the mozzarella cheese and proscuitto.
In a 9-inch frying pan, heat 2T of the butter and 2T of the olive oil; Add the spaghetti mixture and smooth the top with a spatula; Cook over medium-low heat until the frittata is browned on the bottom and set.
Invert a plate larger than the frying pan over the pan and turn out the frittata; Heat the remaining butter and olive oil in the pan, and return the frittata to the pan to brown the other side.
Shake the pan occasionally to keep the frittata from sticking.
Rather than turning the frittata, place the pan under the broiler for 5- 8 minutes.
Invert a serving plate over the frying pan and carefully turn out the frittata; Serve at room temperature, cut in wedges.
NOTE: This is even better the day after it is made.