To prepare the zucchini, shred the zucchini using the course side of a box grater.

Place in a large non-reactive bowl and sprinkle with 3 tsp of salt. Stir to mix in the salt and allow to sit of 30 minutes.

Using cheesecloth and working in batches wring out as much liquid from the zucchini as you can. Reserve 1 cup of the zucchini water and set it aside.

Preheat the oven to 425 degrees F. Grease an 8 x 11 baking dish or equivalent and set aside.

Cook the rice as per the package directions but only allow simmering for 5 minutes then remove it from the heat and drain any remaining water. The rice should be quite al dente. Set aside.

In a medium saucepan heat the butter and olive oil over medium-low heat. Add the diced onions and sauté, stirring often until they are soft, translucent, and are just beginning to caramelize. Add the garlic and continue to cook for 1 – 2 minutes more.

Stir in the flour and continue to cook for another 1 – 2 minutes.

Add the white wine and stir constantly so as to prevent the flour from clumping, then add the reserved zucchini liquid, and half and half.

Continue to stir the mixture over medium-low heat until it simmers and begins to thicken.

Stir in the shredded zucchini, rice, Kosher salt, and fresh ground pepper.

Once the mixture is well-combined add in 3/4 cup of the parmesan cheese.

Spoon the mixture into the prepared baking dish and smooth the top.

Sprinkle the remaining parmesan cheese on top and drizzle with olive oil.

Bake on the middle rack for 20-30 minutes. The casserole should be bubbling and starting to brown on top.

Remove it from the oven and allow it to rest for 10 minutes before serving, this will let any excess liquids in the dish be absorbed.