Trim 2 inches off the ends of the broccolini stems and cut any thick stalks in half lengthwise. Place the broccolini in a single layer on two sheet pans. (If you put them on one sheet pan, the broccolini will steam rather than roast.) Drizzle each sheet pan with 2 tablespoons olive oil, sprinkle with 1 teaspoon salt and 1/2 teaspoon pepper, and toss well. Roast for 15 minutes, until the broccolini is crisp-tender. Sprinkle lightly with salt and serve hot.