Preheat your oven to 200°C (390°F). Slice the zucchinis in half lengthwise and carefully scoop out the centers using a spoon or melon baller, leaving about 1/4 inch of flesh attached to the shell. Set the hollowed-out shells on a parchment-lined baking sheet.
Chop the scooped zucchini flesh into small pieces and set aside. In a large skillet, heat the olive oil over medium heat until it shimmers and smells fragrant. Add the chopped zucchini and minced garlic, cooking for about 5 minutes until softened and slightly caramelized around the edges, with a fragrant aroma filling the air.
Transfer the cooked zucchini mixture to a mixing bowl. Stir in the shredded cheese, breadcrumbs, chopped herbs, lemon juice (if using), and season with salt and pepper. Mix everything until well combined, creating a savory, slightly sticky filling.
Divide the filling evenly among the zucchini shells, pressing gently to pack the mixture into each shell. Place the filled zucchini on the prepared baking sheet, cut side up.
Bake in the preheated oven for about 25–30 minutes, until the tops are golden brown and bubbling with melted cheese. Check at the 20-minute mark and tent loosely with foil if the tops are browning too quickly.
Remove from the oven and let rest for 5 minutes. This allows the filling to set slightly, making it easier to serve. Garnish with extra herbs if desired, and enjoy these rustic, cheesy zucchini boats while warm.
