Pre-heat oven to 425F (210C). Lightly oil or line with parchment paper a medium baking dish.
Place cut side up onions in a single file in baking dish, sprinkle with minced garlic, oregano, salt, chopped rosemary and drizzle with olive oil.
Bake for approximately 30-30 minutes or until onions are tender and dark golden brown. Serve immediately. Enjoy!
Notes
Cool roasted onions completely then transfer to an airtight container and store in the refrigerator for 3 to 5 days. Reheat or enjoy them cold on salads, in wraps or use them in French onion soup.Freeze cooked onions by first flash freezing them on a parchment paper lined pan. Then transfer to a freezer safe bag and store them for up to 1 year. Thaw in the refrigerator before reheating and serving.