Prepare the oven and baking sheet. Preheat the oven to 400°F (200°C). Coat a baking sheet with nonstick cooking spray. If available, position a baking or cooling rack over the sheet to encourage better airflow around the meatballs and promote more uniform cooking.

Combine the meatball mixture. Place the ground turkey, prepared stuffing, chopped spinach, egg, garlic salt, and 1 teaspoon dried rosemary in a large mixing bowl. Stir with a spoon or mix by hand until the ingredients are evenly distributed throughout the turkey mixture.

Shape the meatballs. Portion the mixture into evenly sized balls measuring approximately 1½ inches across. Arrange them on the prepared baking sheet, leaving a little space between each one.

Bake until cooked through. Place the tray in the preheated oven and bake for 18–20 minutes, or until the turkey meatballs are fully cooked and lightly browned. Remove the tray from the oven and allow the meatballs to cool briefly while the glaze is prepared.

Combine the glaze ingredients. Add the cranberry sauce, orange juice, brown sugar or maple syrup, cornstarch-and-water slurry, 1 teaspoon dried rosemary, and ground cinnamon to a medium saucepan. Whisk until thoroughly combined.

Cook and thicken the glaze. Set the saucepan over medium heat and bring the cranberry mixture to a boil, whisking frequently. Allow it to boil for approximately 60 seconds, until thickening begins. Reduce the heat and simmer for another 2–3 minutes, stirring regularly, until the sauce develops a thick, glossy consistency.

Coat or serve the meatballs. Add the baked turkey meatballs to the warm cranberry-orange glaze and gently toss until evenly coated. Alternatively, serve the meatballs warm with the glaze alongside for dipping.