Roasted Potatoes with onion

1 1/2 lbs potatoes , small and firm 2 tablespoons butter 2 tablespoons olive oil 2 red onions , cut into chunks 8 cloves garlic , unpeeled 2 tablespoons fresh[...]

2 lbs small red potatoes 1 red onion , large, cut in 1-inch pieces 8 garlic cloves , chopped 2 tablespoons fresh rosemary , chopped 6 tablespoons olive oil 2[...]