01 -
Preheat oven to 375°F (190°C). Slice each zucchini in half lengthwise, then scoop out the center of each half, leaving about a 1/4-inch border to form boats. Place the zucchini halves on a baking sheet.
02 -
Heat olive oil in a skillet over medium heat. Add the chopped onion and cook until softened, about 3 minutes. Add garlic and cook for another minute until fragrant.
03 -
Stir in the mushrooms and cook until tender, about 4 minutes. Add the spinach and cook until wilted, about 2 minutes.
04 -
Remove from heat and add breadcrumbs (if using) and Parmesan cheese. Season with salt, pepper, and Italian herbs. Stir well to combine all ingredients.
05 -
Spoon the spinach and mushroom filling evenly into each zucchini boat, pressing gently to pack the mixture.
06 -
Sprinkle mozzarella cheese over each zucchini boat. Cover the baking sheet with foil and bake for 20 minutes. Remove the foil and bake for an additional 5-10 minutes, or until the zucchini is tender and the cheese is melted and golden.
07 -
Allow the zucchini boats to cool slightly before serving.