Chicken Enchilada Zucchini Boats

Name: Chicken Enchilada Zucchini Boats
Ingredients: 4 medium zucchini (2 1/2 lbs), sliced in half through length*; 2 cups cooked and shredded chicken (from about 1 lb); 1 1/2 Tbsp olive oil; 2 cloves garlic; 1 1/4 cups shredded Mexican blend cheese; 1/2 cup finely chopped yellow onion (be sure they are chopped fine or they won't cook through); 1 Tbsp ancho chili powder; 1 tsp ground cumin; 1/2 tsp paprika; 1 Tbsp chili powder; 2/3 cup water; 1 1/2 tsp cornstarch; Salt and freshly ground black pepper; 2/3 cup frozen corn; 1 (15 oz) tomato sauce