Preheat the oven to 350 degrees Fahrenheit. Line a baking sheet with parchment paper.
Cut spaghetti squash in half lengthwise and scoop out seeds. Rub cut side with olive oil and place cut side down on baking sheet. Bake for 40-45 minutes or until fork tender.
Meanwhile, add oil to a large, deep skillet over medium-high heat. Sauce the onion, green pepper, and mushrooms until tender, about 5 minutes.
Stir in the cumin, cayenne, and garlic. Cook another 1 minute.
Stir in the black beans, enchilada sauce, hot sauce. Cook another 1-2 minutes to heat everything up.
Scrape insides out of the cooked spaghetti squash using a fork and add to the skillet with the bean mixture. Stir well to mix everything together. Turn off the heat and divide filling between the 2 squash shells.
Top with cheese and put under the broiler on low until cheese is melted.
Serve with desired toppings: sliced black olives, chopped cilantro, sour cream, and hot sauce.