Preheat the oven to 350˚F. Lightly coat a 9 by 13-inch casserole dish with olive oil. Add zucchini to the baking dish, then add 1 tablespoon of olive oil and toss to coat. Season the zucchini with Italian seasoning, ¼ teaspoon salt and ¼ teaspoon pepper. Toss to evenly distribute the spices and set aside.

In a medium saucepan, add butter and set over medium-low heat. Once the butter has melted, add the flour and stir constantly until the mixture turns lightly golden brown and smells slightly nutty. Whisk in the milk, garlic and lemon zest and cook, stirring almost constantly, until the mixture has thickened and can coat the back of a spoon, about 5 to 7 minutes. Remove from heat and season to taste with salt and pepper.

Pour the cream sauce over the zucchini. Mix the remaining olive oil with the parmesan cheese and breadcrumbs, and sprinkle on top of the zucchini.

Bake for 40 to 45 minutes, or until the zucchini is tender (but not mushy), the sauce is bubbling, and the breadcrumbs are golden brown.