Use a sharp knife to carefully slice each zucchini in half lengthwise, creating boat-shaped halves. Scoop out the insides with a spoon, being gentle to avoid tearing the flesh, and set the insides aside for the filling.
Brush the cut sides of the zucchini halves lightly with olive oil, then place them cut-side down on a hot grill. Grill for about 4-5 minutes until the flesh develops beautiful char marks and slightly softens, creating a smoky, crispy edge.
Meanwhile, chop the scooped zucchini insides into small pieces. In a bowl, mix the chopped insides with minced garlic, shredded cheese, breadcrumbs, herbs, salt, and pepper until well combined.
Once the zucchini shells are grilled and charred, flip them over and gently stuff each boat with the prepared filling, pressing it in to fill the cavity completely.
Return the filled zucchini boats to the grill, cooking for another 4-5 minutes until the cheese melts, the filling is heated through, and the tops are golden and crispy.
Remove the zucchini from the grill and let them rest for a minute. Serve hot, garnished with extra herbs if desired, and enjoy the smoky, cheesy, crispy bites.