Preheat your oven to 400°F (200°C). Peel and cut the sweet potato into cubes, then toss with a drizzle of olive oil, salt, and pepper.
Spread the sweet potato cubes on a baking sheet and roast in the oven for about 25-30 minutes, or until tender and slightly caramelized.
While the sweet potatoes roast, finely chop the garlic, onion, and parsley. In a mixing bowl, combine the lean ground turkey with the chopped garlic, onion, parsley, and the egg white. Season with salt and pepper.
Using your hands, gently form the turkey mixture into small meatballs, about the size of a golf ball.
Heat a non-stick skillet over medium heat. If needed, lightly spray with olive oil. Add the meatballs and cook for about 8-10 minutes, turning occasionally, until they are browned on all sides and cooked through.
For the mash, once the sweet potatoes are done, place them in a bowl and mash with a fork or potato masher. Mix in the remaining teaspoon of olive oil and season further if needed.
Serve the warm turkey meatballs over a bed of roasted sweet potato mash. Garnish with additional parsley if desired.