In a fry pan over medium heat, warm the olive oil. Add the onion and sautué lightly until golden, 5 to 8 minutes. Add the garlic and sautué for 1 minute more.

Add the spinach and sautué, stirring, until completely wilted, about 3 minutes. Add the salt and pepper and continue sautuéing for about 2 minutes more.

Place the spinach mixture, parsley, feta cheese and cream cheese in a food processor. Add the hot pasta water. Then season with salt and plenty of black pepper.

Cook the pasta per package instructions. Drain and toss immediately with the green sauce. Sprinkle red hot pepper on top and serve with asiago or parmesan cheese.