I preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper. I slice 4 zucchinis lengthwise and scoop out the flesh with a spoon to form boats. I chop the scooped flesh finely and set it aside. I brush the zucchini halves with a touch of olive oil, place them cut-side up on the baking sheet, and sprinkle lightly with salt.

In a large skillet, I heat 1 tbsp olive oil over medium heat. I add 2 minced garlic cloves and sauté for 30 seconds until fragrant. I toss in 1 cup chopped mushrooms and the reserved zucchini flesh, cooking for 5–7 minutes until the mushrooms are tender and liquid evaporates. I add 2 cups chopped spinach and cook for 2–3 minutes until wilted. I season with ½ tsp oregano, ¼ tsp salt, and ¼ tsp pepper, then let cool slightly.

In a large bowl, I mix the sautéed veggies with 1 cup ricotta and ½ cup Parmesan (if using). I stir gently to keep the ricotta fluffy and taste to adjust seasoning if needed.

I spoon the filling into the zucchini halves, mounding it slightly. I sprinkle extra Parmesan on top if desired. I cover the baking sheet loosely with foil and bake for 25 minutes. I remove the foil and bake for 10–15 minutes more, until the zucchini is tender and the tops are golden.

I serve warm, garnished with fresh parsley or basil for a vibrant touch.