Preheat oven to 375°F (190°C). Pierce each potato several times with a fork. Microwave on high for 8 to 10 min. or until fork tender. Meanwhile, blanch rapini in a saucepan of boiling water for 2 min. Drain, rinse under cold water and spread on paper towel to dry.
Combine beans, milk, salt, pepper and garlic in the bowl of a food processor; pulse until mixture is smooth. Cut each potato in half lengthwise. Scoop the flesh into the food processor (keeping the skins intact) and add butter; pulse just until smooth and well combined. Gently stir in rapini, pine nuts and raisins.
Divide potato mixture evenly between potato shells and top each filled potato with an equal amount of Parmesan cheese. Bake for 15 min. or until heated through.