Preheat oven to 350 degrees F.
To shred the apple, either use the shredder plate for your food processor or manually grate using a cheese grater. Add to a large mixing bowl.
Add grated parmesan, pulsed oats (again, these can be made using a food processor), whisked egg, ground turkey, fresh rosemary, and salt and pepper. Form into small balls.
Place oil in a cast-iron skillet over medium-high heat. Once oil is hot, carefully place meatballs in pan, being careful not to overcrowd. If your pan isn’t big enough, you can split this up into two batches, using 1/2 Tbsp of oil per batch. Cook until all sides are browned, about 5 minutes.
Transfer skillet to oven (if oven-proof; otherwise transfer meatballs to a baking sheet) and cook another 8-10 minutes, or until cooked through.
Remove meatballs from oven and serve with roasted vegetables and dipping sauce of choice. Enjoy!