Cut each zucchini in half lengthwise and hollow out the center using a spoon to create a "boat". Lay each half, face-up, on a baking sheet and season with salt and pepper.
Bake in the preheated oven until hot and slightly tender, about 10 minutes.
Stir tomatoes, crackers, corn, olives, mushrooms, salsa, garlic, Italian seasoning, and oregano together in a bowl. Season with salt and pepper.
Cook and stir tomato mixture in a skillet over medium heat until all liquid evaporates, 5 to 10 minutes. Spoon tomato mixture into zucchini "boats". Top each "boat" with Gouda cheese.
Bake stuffed zucchini "boats" in the oven until tender and cheese is melted, about 15 minutes.
