Step 1

Preheat the oven to 375°F and coat a shallow baking sheet with nonstick spray.

Step 2

Halve the zucchini lengthwise and, using a melon baller, hollow out each half, leaving a wall of about 1/4-inch on the sides and bottom. Reserve the flesh you removed.

Step 3

Season the zucchini halves with salt, arrange them on the prepared baking sheet and set aside for 10 minutes to allow some of the moisture to be drawn out.

Step 4

Blot the zucchini dry with paper towels, then bake until softened, 8 to 10 minutes. Remove from the oven and set aside.

Step 5

While the zucchini pre-bakes, roughly chop the reserved zucchini flesh.

Step 6

Heat the butter in a large frying pan over medium heat and add the onion. Sauté until soft and translucent, 4 to 6 minutes.

Step 7

Add the garlic and continue cooking for 1 minute longer, then add the zucchini.

Step 8

Season the mixture with salt and pepper and continue cooking until the entire mixture is soft and slightly caramelized, 4 to 5 minutes longer.

Step 9

Sprinkle with breadcrumbs, 3/4 cup of the shredded cheese and all of the Parmesan. Combine well.

Step 10

Divide the zucchini-onion mixture between the hollowed "boats," and top each with a sprinkling of the remaining cheese.

Step 11

Return the zucchini to the oven for an additional 8 to 10 minutes, or until the "boats" are tender when pierced with a knife and the cheese is melted and golden.