Heat olive oil in a cast iron skillet over medium-high heat.
Add ground turkey and garlic, breaking the meat apart as it cooks for about 5 minutes.
Stir in onions and yellow pepper; cook until softened.
Add diced sweet potatoes, salt, pepper, and chili flakes.
Cover and cook, stirring occasionally, until sweet potatoes are tender. Add a splash of water if needed.
Preheat oven to 400°F (200°C).
Once tender, sprinkle mozzarella cheese over the skillet.
Transfer to the oven and bake until cheese melts.
Remove, garnish with parsley, and serve warm.