01 - Preheat the oven to 375°F.
02 - Heat olive oil in a large skillet over medium heat. Add onion and garlic; sauté for 2–3 minutes until fragrant.
03 - Add ground turkey. Cook, breaking up with a spoon, until no longer pink, about 5–6 minutes.
04 - Stir in diced zucchini, bell pepper, and drained tomatoes. Cook for 5 minutes until vegetables start to soften.
05 - Add Italian herbs, paprika, salt, and black pepper. Stir to combine thoroughly.
06 - Remove skillet from heat. Mix in sour cream and half of the mozzarella cheese until evenly distributed.
07 - Transfer the mixture to a greased 9x13-inch baking dish, spreading evenly.
08 - Sprinkle remaining mozzarella and all of the Parmesan evenly over the top.
09 - Bake for 25–30 minutes, or until the casserole is bubbly and the cheese is golden brown.
10 - Let cool for 5 minutes before serving to allow the casserole to set.