Preheat the oven to 425°F (220°C). Line a large baking sheet with parchment paper or foil and lightly coat it with cooking spray.

In a large mixing bowl, combine the egg, ¼ cup apple cider, panko breadcrumbs, Dijon mustard, grated apple, kosher salt, black pepper, garlic powder, and onion powder.

Add the ground turkey. Gently mix until the ingredients are evenly incorporated. Avoid overworking the turkey, which can make the finished meatballs dense.

Scoop approximately 2 teaspoons of the turkey mixture at a time and gently roll it into balls. Arrange the meatballs on the prepared baking sheet with a little space between each one.

Bake for approximately 12–15 minutes, or until the meatballs are fully cooked and reach an internal temperature of 165°F (74°C).

While the meatballs bake, prepare the apple cider glaze. Add 1 cup apple cider, 2 tablespoons additional apple cider, soy sauce, maple syrup, apple cider vinegar, ground ginger, and cinnamon to a medium saucepan.

Whisk the ingredients together and bring the mixture to a gentle boil.

In a small bowl, whisk the cornstarch with 1 teaspoon cold water until completely smooth.

Slowly pour the cornstarch slurry into the bubbling cider mixture while whisking continuously.

Reduce the heat to medium and continue cooking, whisking frequently, until the apple cider glaze becomes glossy and thick enough to coat the back of a spoon.

Add the baked Apple Cider Turkey Meatballs to the saucepan. Gently toss until each meatball is covered with the sticky glaze.

Reduce the heat to medium-low and simmer for several minutes, allowing the meatballs to absorb some of the sweet and savory apple cider flavor.

Transfer to a serving dish and garnish with sliced green onions, if desired. Serve warm as an appetizer or main course.