Stuffed Peppers with Turkey and Vegetables

Name: Stuffed Peppers with Turkey and Vegetables
Ingredients: 4 green bell peppers, tops removed, seeded; 1 pound ground turkey; 2 tablespoons olive oil; 0.5 onion, chopped; 1 cup sliced mushrooms; 1 zucchini, chopped; 0.5 red bell pepper, chopped; 0.5 yellow bell pepper, chopped; 1 cup fresh spinach; 1 (14.5 ounce) can diced tomatoes, drained; 1 tablespoon tomato paste; Italian seasoning to taste; garlic powder to taste; salt and pepper to taste