Preheat oven to 400 degrees F (204 C).
Place cleaned mushrooms on a baking sheet and lightly drizzle both sides with a little olive oil. Sprinkle with garlic powder, basil, and oregano. Then bake for 5 minutes.
In the meantime, prep the veggies as specified above. Once part-baked, pull mushrooms out of the oven and top with desired amount of pizza sauce, veggies, and 1⁄4 cup cheese.
Bake for 15-20 minutes, or until the veggies are mostly cooked. Top with fresh basil if desired.