Preparation Bring 6 cups vegetable broth to a simmer. Melt 3 tablespoons butter in a large saucepan over medium-high heat. Add 1/2 medium cantaloupe (peeled, seeded, grated), 2 chopped shallots, and 1 chopped garlic clove; cook, stirring, until liquid is thickened, 8-10 minutes. Add 2 cups arborio rice and 1/4 cup dry white wine; cook for 2 minutes. Add broth by 1/2-cupfuls, stirring often and cooking until liquid is almost absorbed before adding more, until all broth has been added and rice is tender, 25-30 minutes. Stir in 1/4 cup mascarpone and 1 ounce. chopped prosciutto; top with thinly sliced basil.