Snap both ends of the green beans and pull the strings. Soak in cold water and drain well. Peel the carrots and wash them in cold water. Cut into sticks of about the same size as the green beans. In a small skillet, heat the butter and toss in the chopped prosciutto. Add vegetables and saute until crisp tender. Season lightly with salt and pepper and serve with a sprinkling of finely chopped basil on top of them.