To prepare asparagus spears, snap off and discard wood bases. Scrape off scales. Place asparagus, onion and sweet pepper in a 15x10x1-inch baking pan. Drizzle with olive oil, toss gently to coat. Spread in a single layer. Sprinkle with salt and pepper.
Roast, uncovered in a 400 degree F oven for 20 minutes or until asparagus is crisp-tender. Transfer to a serving platter; sprinkle with cheese. Let stand 2 minutes until cheese melts. Serve hot.