Chop the top half inch off the head of garlic and place it in a microwave-safe bowl. Drizzle the top with olive oil and cover the bowl. Microwave on high, one minute at a time, until the garlic cloves are soft (poke them with a fork to save burning yourself).
Remove the garlic from the microwave and set aside to cool.
Cook the pasta according to package directions. Drain, but save 1/2 cup of the cooking water and put the pasta back into the pot with the burner now off.
While cooking the pasta, squeeze the garlic cloves, and they’ll pop easily out of the skin. Mince the garlic and place it into a mixing bowl.
Add the ricotta, salt and pepper, and 1/2 cup pasta water to the mixing bowl and stir until smooth.
In the warm pot you cooked the pasta in, add the spinach, ricotta sauce and cherry tomato halves to the pasta and stir so that everything is coated well and the spinach starts to wilt.
Add the parmesan cheese and more salt and pepper if needed.