Bring a large pot of salted water to boil. Add the Ronzoni and cook until it is tender but still firm to the bite, stirring occasionally, about 12 minutes.
Mince the garlic in a food processor. Add the cream cheese, 3/4 teaspoon of salt, 1/2 teaspoon of pepper, add fresh parsley, and half of the spinach leaves. Blend until the mixture is smooth and creamy. Set the cheese and spinach mixture aside.
Meanwhile, place the remaining spinach leaves in a large bowl.
Drain the pasta, reserving 1 cup of the cooking liquid. Spoon the pasta atop the spinach leaves in the bowl. Scrape the cheese and spinach mixture over the pasta mixture and toss to coat, adding enough reserved cooking liquid to moisten. Season the pasta, to taste, with salt and pepper. Sprinkle the Feta over top and serve.