Stuffing zucchini turns a basic vegetable into a favorite meal. Grilling it on a plank keeps the zucchini crisp tender and protects the delicate vegetable from overcooking. The stuffing browns at the same time as the edges of the zucchini and nothing gets soggy like it does in the oven. You can use this same stuffing for red and yellow peppers—but it will yield less, about 4. The sausage can be left out of the stuffing for a vegetarian option.
Trim off the ends of each zucchini. Cut each in half crosswise. Cut each piece in half lengthwise. Scoop out the centers, leaving a shell at least 1/4-inch thick.
Reserve the scooped-out portions and set aside. Clean and roughly chop the mushrooms and set aside.
Melt half the butter in a heavy skillet and add the mushrooms. Stir and cook about 5 minutes. Remove to a large mixing bowl.
Melt the other half of the butter in a heavy skillet, and add the onions and garlic. Cook for about 5 minutes, stirring, add the chopped zucchini, thyme, salt and pepper. Cook about 3 minutes until the excess moisture evaporates. Place in the bowl with the mushrooms, and set aside.
Add the sausage to the skillet and cook over medium heat, breaking up the meat. Cook until no longer pink, about 5-7 minutes. Scrape the sausage into the mixing bowl, and stir the mushrooms, and onion mixture to combine. Let cool slightly. Add the panko bread crumbs, the parsley and the cheese, and blend thoroughly. Taste for seasoning and add salt and pepper if necessary. This is important because it may not be necessary. The Italian sausage and cheese may have enough salt for the entire mixture—mine did. Let cool.
Note: I place the stuffing in a food processor and pulse/chop to mix and break up large pieces, but you don’t have to do this. Be careful not to let it process too much. You don’t want it to puree the filling, but I use it to make the stuffing more uniform.
Brush the inside and outside of the zucchini shells with olive oil. I do this by placing them in 1-2 re-sealable plastic bags and drizzling oil in the bag and rubbing it all over the zucchini boats.
Using clean hands, or using kitchen gloves, grab a small handful of the mixture and press lightly to compress a little, you want to make a “torpedo” shape that will fit the area that you spooned out. Fill each shell, press to secure and make a slightly curved top—you don’t want it to be flat because there won’t be enough filling. This can be done in advance and refrigerated, well-wrapped, overnight.
In a sink or container large enough to hold the planks, immerse the planks in water for 30 min. or longer (you may need to weigh it down).
When ready to cook, preheat the grill according to instructions.
Place the zucchini boats on a soaked plank and place in the center of the cooking grate. Close the lid and let grill for about 25 minutes or until the top is crisp and browned and you see brown spots on the zucchini.
Serve hot or at room temperature. You can freeze any extra stuffed zucchini and cook them from frozen on a soaked plank, but be sure to add about 10 minutes to the cooking time.