Prep zucchini: Wash 6 small-medium zucchini well, then slice in half lengthwise. Scoop out flesh with a small spoon and set aside. Place zucchini halves on baking sheet.
Brown beef and season: Heat 1 tablespoon olive oil in large skillet over medium-high heat. Add 1 onion and cook until softened, then add 1 pound ground beef and cook until well browned. Stir in 2 tablespoons tomato paste, 2 tablespoons chopped fresh basil, 1 teaspoon dried Italian herbs, ½ teaspoon garlic powder, ½ teaspoon salt and pepper.
Finish filling: Stir in 1 (15oz) can tomato sauce and scooped out zucchini flesh (chop if desired for more even filling), then simmer, covered, on low heat for 10 minutes. Remove the lid, stir well and simmer for another 5 minutes.
Fill and bake: Heat oven to 360°F. Spoon filling in prepared zucchini halves. Sprinkle with 1.5 cups shredded cheese and bake 20-25 minutes until bubbly.
