Cook the pasta (I used macaroni) according to the package's instructions (about 8-10 minutes), until al dente.
Place the spinach leaves in the bottom of a strainer, and pour the pasta over top to drain and wilt the spinach. Save about 1/2 cup of the pasta water. Return the cooked macaroni and wilted spinach to the pot.
Add about 1/4 cup of the reserved pasta water to the pot, and stir in the cheese until melted. Stir in the greek yogurt, onion powder, garlic powder, salt, and pepper, until smooth and creamy. Stir in the remaining pasta water to thin, if necessary. Serve immediately.