Preheat the oven to 400°F. Spray a rimmed baking sheet with nonstick cooking spray. Place the vegetables on the baking sheet, drizzle over the 2 tablespoons olive oil, sprinkle with salt and bake for about 20 minutes, until the vegetables are tender and just slightly golden.
While the vegetables are roasting, make the drizzle. Place the olives, shallots and rosemary in a blender or a food processor and blend to chop everything finely. Add the olive oil and the pepper and puree until it is fairly smooth (it won’t get all the way smooth; that’s fine).
Transfer the vegetables to a serving platter, and either drizzle over the olive sauce, or pass it on the side, or drizzle over a little and pass the rest (that’s what I usually do, but if you think some of your gang won’t go for it, leave it on the side). Serve hot, warm or room temperature.