To a large mixing bowl, add the 22 ounces of grated zucchini along with 2 tsps kosher salt. Gently toss to combine, then let this sit for 5-10 minutes. Once there is visible liquid in the bottom of the bowl, place a strainer over a measuring cup or bowl and line the strainer with a clean kitchen towel or cheesecloth.
Carefully pour the grated zucchini and juice into the lined strainer. Gently press the zucchini shreds down, then wrap the zucchini in the towel and squeeze out as much juice as you can. Ideally, you should yield about ¾-1 cup of green zucchini juice. Keep the juice and set aside.
Heat a large pan with high sides or a dutch oven over medium heat. Add 2-3 tbsp olive oil and then add the squeezed shredded zucchini. Use a spatula to spread it into an even layer. Allow to cook without touching until the zucchini just begins to brown.
Stir the zucchini and continue to cook over medium heat for about 5 minutes or until it is very soft and has begun to take on a darker/yellow color. Lower the heat and add 2 cloves of grated garlic, stirring to combine.
Meanwhile, bring a large pot of salted water to a boil. Cook the 6 ounces of spaghetti about halfway. The noodles should have a slight bend to them, but they should still be very firm and unpleasant to eat. Reserve some of the pasta water.
Using tongs, add the noodles directly to the pot of cooked zucchini. Pour the green zucchini juice over the noodles. Increase the heat to high and allow the noodles to finish cooking in the sauce, stirring carefully as to not break the noodles.
Once the spaghetti has absorbed the green liquid and is cooked to al dente, lower the heat and add ½ cup of grated parmesan. Stir the cheese in slowly, using any reserved pasta water if you have it. Then, stir in the heavy cream, half of the sliced basil, a pinch of kosher salt (to taste) and black pepper (to taste).
In a small pan, heat 1-2 tbsp olive oil and add ¼ cup panko breadcrumbs. Toast until the panko is golden brown, then remove and pour into a bowl. Season with a pinch of salt. Once cooled, add 3 tbsp grate parmesan and stir.
Serve the pasta warm and garnish with a squeeze of lemon, the remaining basil, and the toasted breadcrumbs.