Zucchini Au Gratin Recipe (Cheesy Zucchini Tian)

• Spray a large (8-10 cup) casserole dish with nonstick cooking spray. Heat oven to 400°F and position oven rack to upper third position.

Prepare the zucchini

• Cut off the stem and tip from each zucchini. Gently scrub the zucchini and peel. Note: If the zucchini is unpeeled, the color of the finished casserole will be much greener.
  2-2½ pounds zucchini
• If available, use a food processor to grate the zucchini. If a food processor isn’t available, rub the zucchini against the coarse side of a grater.

  Place the grated zucchini in a large colander set over a large bowl. Sprinkle 1-teaspoon kosher salt over the zucchini and toss together until mixed thoroughly. Allow the squash to drain at least 10 minutes or even overnight (covered).

  Line a large baking sheet with 3 layers of paper towels. Remove the colander from the bowl and squeeze the grated zucchini, one handful at a time. Reserve this zucchini juice for later use.

  Place the squeezed zucchini on the prepared baking sheet and repeat until excess juice has been drained from all the grated zucchini. Cover the zucchini with 2 layers of paper towels and press down. Set the zucchini aside until ready to cook.

Prepare to assemble and bake

• While the zucchini rests, cook the rice according to package directions minus 5 minutes less than directed. Remove the rice from the heat and stir.
  1 cup uncooked long-grain white rice
• While the rice cooks, heat a large skillet over medium-low heat and add 3 tablespoons oil. When the oil is hot, add the diced onion and cook 8-10 minutes or until tender, translucent and beginning to brown lightly.
  3 tablespoons olive oil, 1 cup diced onions
• Add the minced garlic. Cook an additional 30 seconds and keep stirring.
  2 large cloves garlic
• Add the dried zucchini and mix well. Cook 5-6 minutes or until the zucchini is almost tender.
• Sprinkle the zucchini with the flour and mix well. Cook and stir for 2 more minutes. Remove from the heat.
  3 tablespoons flour
• Heat the milk and 1 cup reserved zucchini juice in the microwave (or stovetop just until warm). Add the milk/juice to the zucchini mixture and stir until incorporated.
  1¼ cups whole milk, 1 cup reserved zucchini juice
• Set the pan over medium-low heat and add the par-cooked rice. Stir and cook about 5 minutes or until most of the excess liquid has reduced. Watch closely so it doesn’t scorch.
• Remove from the heat and add ¾ cup grated Parmesan cheese. Stir well and season to taste with kosher salt & freshly ground black pepper, if needed.
  1 cup grated Parmesan cheese, Kosher salt and freshly ground black pepper
• Transfer zucchini/rice mixture to greased dish, sprinkle evenly with reserved ¼ cup grated Parmesan and drizzle with olive oil.
  2 tablespoons olive oil
• Bake 30-40 minutes at 400°F or until bubbly throughout and top is golden brown. (If the casserole looks heated through and bubbly, but the top is still somewhat pale, set the oven to broil and cook another 2-3 minutes. Watch very closely until the zucchini is golden brown and gorgeous on top.)