Mix the ricotta with a blender (or by hand with a whisk), with olive oil, vinegar, salt, and pepper, until you get a yogurt-like consistency. If it is not soft enough, mix in 1 to 2 tablespoons of warm water.
In a large bowl, stir the spinach into the ricotta mixture and set it aside.
In a large pot of salted water, cook pasta according to package directions for al dente pasta. Scoop some pasta cooking water out of the pot with a heatproof measuring cup, then drain the pasta. Combine the pasta with the ricotta and spinach mixture in the bowl.
Stir in the parmesan cheese, adding some of the reserved pasta water, if needed, to smoothly mix the parmesan with the pasta and ricotta.
Divide the pasta into two serving dishes, top each with a tablespoon of ricotta and some freshly ground black pepper, and serve.
