Baked stuffed red onions

Ingredients

• 8 small red onions, skin removed
• 1/3 cup dried cranberries
• 1 clove garlic, finely chopped
• 1/4 pine nuts
• 1/4 dark cane sugar
• salt and freshly ground black pepper
• 1/4 cup balsamic vinegar
• 8 small sprigs of rosemary
• 25 gram butter