Cut the tops off the peppers and scoop out seeds and membranes, then rinse and pat dry. Place them upright in a baking dish.
Dice the onion and mince the garlic, then heat oil in a skillet over medium heat until it shimmers and smells fragrant.
Add the diced onion and minced garlic to the skillet, sautéing until translucent and fragrant, about 3-4 minutes, with gentle sizzles.
Add the ground turkey to the skillet, breaking it apart with the spatula, and cook until browned and cooked through, about 6-8 minutes, stirring occasionally.
Stir in tomato paste, smoked paprika, cumin, salt, and black pepper, cooking for another minute until the spices are fragrant and the mixture darkens slightly.
Spoon the turkey mixture into each hollowed pepper, pressing gently to pack the filling inside. If using cheese, sprinkle it on top now.
Place the filled peppers in the preheated oven at 200°C (400°F) and bake for 25-30 minutes, until the peppers are tender and slightly blistered at the edges.
Remove from oven and let rest for about 5 minutes; this helps the juices settle and makes handling easier.
Sprinkle chopped parsley over the peppers for a fresh herbal finish, then serve hot, perhaps with a side salad or crusty bread.
