Preheat the oven to 350F.
Cook the pasta according to package instructions until it is JUST al-dente. It will cook a bit more as it bakes in the oven.
While the pasta is cooking, make your ziti by adding the spinach, basil, Pecorino cheese, oregano (optional), garlic, pine nuts, olive oil, and lemon juice to a food processor. Pulse until fully combined. You want this to be thicker than a traditional pesto, because you are going to mix it into your ricotta. Season to taste. (Note: if you don't have a food processor, or just don't feel like making your own, you can sub store bought pesto).
In a large bowl, combine the pesto with the ricotta cheese. Stir to combine.
Once the pasta is cooked, strain the pasta and add it to your ricotta and pesto mixture.
Spray a oven-safe baking dish - I use a 9.5 inch round baking dish for this (so you can use anything that is a similar size) - and add the pasta mixture to the dish.
Top with the sliced mozzarella and additional grated Pecorino.
Bake for about 15-20 minutes, or until the cheese is bubbling and the top begins to brown. I like to broil for the last minute to really get the cheese gooey.
Slice and serve! It's great topped with a squeeze of extra lemon!