Using on/off turns, puree olive oil, 1/3 cup basil, and shallot in processor until basil and shallot are finely chopped.
Cut each cantaloupe wedge crosswise in half. If using large mozzarella ball, trim and cut into 6 cubes. Alternate 1 melon piece, 1 piece ruffled prosciutto, 1 mozzarella ball or cube, 1 more prosciutto piece, and 1 more melon piece on each skewer. (Can be prepared 2 hours ahead; cover and refrigerate. Bring to room temperature 15 minutes before serving.)
Arrange skewers on platter. Drizzle with basil oil and sprinkle with cracked black pepper. Garnish with basil sprigs.
*Available at Italian markets, cheese shops, and some supermarkets.