Step 1: Prepare Bell Peppers: Wash bell peppers and cut off the tops. Remove seeds and membranes, keeping the peppers intact. Set aside.
Step 2: Make the Filling: In a large mixing bowl, combine ground turkey, cooked rice, onion, garlic, zucchini (if using), diced tomatoes, tomato paste, Italian seasoning, smoked paprika, salt, pepper, and 1 cup shredded cheese. Mix until everything is evenly combined.
Step 3: Stuff the Peppers: Spoon the filling mixture into each bell pepper, packing it down lightly. Place stuffed peppers upright in the crockpot.
Step 4: Add the Sauce: In a small bowl, mix tomato sauce, Worcestershire sauce, garlic powder, onion powder, and dried basil. Pour the sauce evenly over the stuffed peppers.
Step 5: Slow Cook: Cover and cook on low for 4-6 hours or high for 2-3 hours, until peppers are tender and filling is fully cooked. About 15 minutes before serving, sprinkle extra shredded cheese on top of each pepper, cover, and allow it to melt.