Preheat the oven to 400 degrees.
Slice a zucchini in half, lengthwise. Using a spoon or melon baller, hollow out the center of each zucchini. I do this by cutting close to the edge of the zucchini, leaving a small margin along the sides, and being careful not to cut all the way through the zucchini. In the center, make a slice down the center, then making horizontal slices across the center of the zucchini where you find all the seeds. This will make it easier for you to scoop this center portion out.
Lay the hollowed out zucchinis on a baking sheet lined with parchment paper, foil, or a silicone baing mat. Set aside.
In a large skillet, heat up 1-2 tablespoons of water over medium-high heat. Add the onions, peppers, garlic, and mushrooms. Cook for a couple of minutes, until soft.
Add the pizza sauce, veggie crumbles, Italian seasoning, and salt. Cook for another 3-4 minutes or until hot. Remove from heat.
Inside each zucchini boat, spread a thin layer of additional pizza sauce; season with extra Italian seasoning and/or garlic powder.
Spoon the pizza filling inside each of the zucchini boats until full. Spread on some Pizza Cheez Sauce, if desired. Sprinkle on black olives.
Bake in the oven for 25-45 minutes. The time depends on the size of the zucchini. Test the doneness by pricking the sdes of the zucchini with the tip of a sharp knife.