Boil the pasta water by bringing a large pot of salted water to a rolling boil. Once boiling, add spaghetti and cook according to package instructions.

Prepare the ricotta sauce by combining ricotta, lemon zest, lemon juice, grated garlic, and olive oil in a bowl. Whisk until smooth.

Reserve about 1 cup of pasta water and then drain the pasta.

Blend the sauce with the reserved pasta water over low heat until silky.

Toss the pasta with the sauce until evenly coated and heated through.

If using, toss in spinach during the last minute of cooking for freshness.

Finish with grated Parmesan cheese, adjusting seasoning as needed.

Serve garnished with extra cheese, lemon zest, and a drizzle of olive oil.