Trim the stem end of the zucchini, cut them in half lengthwise, and scoop out a small channel of seeds with a regular teaspoon.
Place the zucchini in one layer on a sheet pan, brush generously all over with canola oil, and turn the zucchini cut side down. Sprinkle with salt and roast for 12 to 15 minutes, until just tender but still firm when tested with the tip of a small paring knife.
Meanwhile, make the bread crumbs mixture. In a medium bowl, combine the garlic, parsley, Parmesan, 1 teaspoon salt, and 1/2 teaspoon pepper. Add the panko and melted butter and mix well.
Turn the zucchini cut side up and carefully spoon the panko mixture evenly on each zucchini. Bake for another 8 to 10 minutes, until the panko is crispy. Serve hot or warm.