Lay zucchini slices on paper towels and sprinkle with salt. Let drain 10-15 minutes and pat dry.
Brush crust with a thin layer of olive oil. Arrange zucchini slices on top. Top with prosciutto and sprinkle with cheese. Bake at 400 degrees 8-10 minutes. Sprinkle with rosemary. Cut in squares or wedges to serve.