Preheat oven to 400 degrees. Spray a 9x13 baking dish with nonstick cooking spray.
Slice zucchini in half lengthwise and scoop out the middle of the vegetable with a spoon or melon baller, leaving about 1/2 inch along the outside creating a “boat.”
Place zucchini in prepared baking dish and brush with olive oil. Sprinkle with salt and pepper. Cook for 10 minutes to soften.
In a large skillet, add ground beef, onion and garlic. Cook until the beef is browned and the onion is soft. Drain.
Return meat mixture to skillet and add taco seasoning as well as diced green chiles, 1/4 cup water, and half of the enchilada sauce. Bring to a boil and simmer for 5-10 minutes or until thickened and excess liquid is evaporated. Remove from heat.
Spoon the beef mixture into the zucchini boats, pressing down to fill. Add extra mixture on top until the boats are overflowing slightly.
Top the zucchini with the remaining enchilada sauce and add a layer of cheese.Bake for 15 to 20 minutes until the cheese is melted and zucchini is tender.
* if the amount of filling is too much for your zucchini, leftover filling can be refrigerated for 1 week, or frozen for several months. You could also increase the amount of zucchini boats.