Heat 1 tablespoon oil in a medium frying pan over a medium-high heat. Add onion, garlic, mushrooms and sage. Cook for about 5 minutes, stirring, until mushrooms are soft. Remove from heat. Transfer to a large bowl. Cool.
Add turkey mince, egg, 1 cup breadcrumbs and ¼ cup cranberry sauce to mushroom mixture. Season with pepper. Mix with clean hands until well combined.
Roll level tablespoons of mixture into balls and toss in remaining breadcrumbs to coat lightly.
Drizzle remaining oil over base of a large, non-stick roasting pan. Heat in a 200C oven (fan-forced) for 10 minutes. Remove from oven. Add meatballs to the hot pan.
Return to oven. Bake for 20-25 minutes, turning meatballs halfway during cooking time, until browned and cooked through.
Meanwhile, heat the extra ½ cup cranberry sauce in small saucepan until warm. Serve meatballs with warm cranberry sauce.

Use wet hands when rolling meatballs if mixture is sticky.
Meatballs can be prepared a day ahead. Place on a baking paper-lined tray, cover and keep refrigerated until ready to cook.
To fry sage leaves for garnish, heat a little olive oil in a small frying pan, add sage leaves and cook over a medium heat for about 30 seconds on each side, until crisp. Drain on paper towel.