toppings: salsa, avocado, sour cream, cilantro, corn, diced tomatoes, etc.
Preheat the oven to 400ºF (204ºC).
Cut each zucchini in half lengthwise, then use a spoon, teaspoon measure, or melon baller to scoop out the seedy centers and discard.
Place zucchini side by side, cut side up, on a large baking sheet or in a large casserole dish. Set aside.
In a large skillet over medium heat, brown the the ground beef. Add the taco seasoning and water, stir until everything is combined, then reduce the heat to low and simmer for 5 minutes.
Remove the beef from heat, then add the rice and stir until everything is combined.
Spoon the ground beef and rice mixture into the prepared zucchini, then bake for 15 minutes.
After the 15 minutes, remove the zucchini from the oven, then top with cheese and return to the oven for 5 minutes or until the cheese is melted to your liking. Add toppings and serve. Store leftovers in the refrigerator up to 5 days. Unbaked zucchini freeze well, up to 3 months. Wrap tightly in plastic wrap or foil to freeze. Thaw in the refrigerator, then continue with baking instructions.