Sprinkle generously with salt and pepper and top with a rosemary sprig. Bake for 25 minutes until bubbling and tender. Drizzle the olive oil over the onions. Place a thin pat of butter on each onion. https://www.nospoonnecessary.com/oven-caramelized-onions-recipe https://www.marthastewart.com/312694/baked-chicken-and-onions https://recipeland.com/recipe/v/french-fried-onions-oven-baked-57217 My Tuscan grandmother served them simply -- sprinkled with good wine vinegar and a little olive oil. Increase the oven temperature to 400 degrees F and cook for another 15 to 20 minutes until the onions are completely tender and the tops are browned. https://www.allrecipes.com/recipe/88280/roasted-vidalia-onions Bursting with lush, rich brown flavors, roasted onions are as versatile as baked potatoes but with fewer calories. I skip the olive oil and use only balsamic vinegar. https://recipes.howstuffworks.com/oven-roasted-peppers-and-onions-recipe.htm Onions are an assertive ingredient, usually used to bring either aggressive astringency or deep, developed umami to a dish. Make them a one-dish meal, a first course, a salad or side dish.