Trim broccoli rabe, removing tough parts of stems and any stems with a hollow core. Split stems (or quarter them if large) so they'll cook at the same rate as the florets. Rinse well.
Bring a large pot of water to a boil over high heat. Add broccoli rabe (you may have to add in batches, waiting until some cooks down) and cook until tender, 2 to 5 minutes. Scoop out and set aside about 1/4 cup cooking liquid, then drain broccoli rabe in a colander. Let sit until cool enough to handle, about 15 minutes, then squeeze gently to remove excess moisture.
Heat oil in a 12-in. skillet over medium heat. Add garlic and chiles and sauté until garlic is golden, about 1 minute. Add broccoli rabe and 1/2 tsp. salt and toss to coat with oil. Increase heat to high and cook until broccoli rabe is heated through and flavorful, about 5 minutes (if it looks dry, moisten with some of the reserved cooking liquid). Season with salt to taste. Serve hot or at room temperature.
