Preheat the oven to 350°F and lightly drizzle a 9 x 13 baking dish with olive oil.
Cut the zucchinis lengthwise and scoop out their insides, leaving around 1/4 inches of flesh on all sides.
Lightly sprinkle the boats with sea salt and arrange on the baking dish.
Heat olive oil in a large skillet over medium heat.
Add the onions and peppers and saute for 10 minutes or until the onions begin to caramelize.
Season with salt and pepper, then stir in the mushrooms. Cook for 4 minutes until the liquids are released.
Add the minced garlic and Italian seasoning. Cook for 30 seconds or until fragrant, then remove from heat.
Wipe out the salt and water from the zucchini boats.
Spread 2 tablespoons of the pasta sauce in the bottom of each zucchini boat. Top with the mushroom mix, tomatoes, olives, and pepperoncini peppers.
Bake for 30 minutes or until the tomatoes burst.
Serve with freshly chopped basil on top, and enjoy!