Working in batches, cook the broccoli rabe in a large pot of boiling salted water until crisp tender, about 2 to 3 minutes per bunch. Transfer the broccoli rabe to a large bowl of ice water to cool. Reserve about 1/4 cup of the cooking liquid. Drain the cooled broccoli rabe and set aside.
Heat the oil in a heavy large skillet over medium heat. Add the garlic and red pepper flakes, and saute until the garlic is golden, about 1 minute. Reduce heat to medium-low. Add the broccoli rabe and toss to coat. Add the reserved cooking water, the raisins, and cook until the broccoli rabe is heated through and the stems are tender, about 4 minutes. Season with salt, to taste. Toss the mixture with toasted pine nuts, serve immediately.