Preheat oven to 400° F. Spray a 9x13-inch baking dish with cooking spray. Scoop out centers of cut zucchini leaving 1/4 inch rim to create the boats. Lay zucchini in baking dish. Bake for 20 to 25 minutes or until tender.
Meanwhile, cook ground beef and onion in a large skillet, over medium-high heat, until browned and crumbled. Drain grease. Add garlic, tomato sauce, chili powder, cumin and paprika. Stir to combine.
In a liquid measuring cup whisk 2/3 cup water and cornstarch together until blended. Pour into beef mixture. Season with salt and pepper. Bring mixture to a boil, then reduce heat to low. Simmer 5 minutes then remove from heat.
Remove zucchini from oven and spoon beef mixture into zucchini. Sprinkle tops with corn and cheese. Return to oven and bake 5 to 10 minutes or until cheese is melted and bubbly. Remove from oven and let stand 5 minutes before serving.
Serve with toppings and enjoy!