1/2 cup Extra virgin olive oil
2 Medium yellow onions (finely chopped)
2 cloves Garlic (finely chopped)
4 quarts Water
1 lb Whole wheat or other spaghetti
2 cups Greek yogurt (at room temperature)
1 cup Freshly grated kefalotiri or Parmesan cheese
1/4 tsp Sea salt (plus more to taste)
1/2 tsp Freshly ground black pepper (plus more to taste)
1/4 cup Chopped fresh Italian flat-leaf parsley (for garnish)

Heat the olive oil in a large skillet or sauté pan set over medium-low heat. Add the onion and cook, stirring frequently, until it is translucent, about 8 to 10 minutes. Stir in the garlic and cook for 1 minute more. Remove from heat and set aside to cool slightly.

Add the water to a large pot and bring to a boil over high heat. When the water starts to boil, liberally salt it. Add the spaghetti and cook for 1 minute less than the package directions, until al dente. While the pasta is cooking, mix together the yogurt, cheese, salt, and pepper in a medium mixing bowl, making sure there are no lumps.

Drain the pasta, reserving 1 cup of the starchy cooking water. Return the hot pasta to its pot, and add the olive oil-onion mixture, tossing to combine well with spaghetti. Quickly add the yogurt mixture, making sure the spaghetti is coated. Very slowly pour in the reserved cooking water, a little at a time, until the desired consistency is reached. You probably will not need all the water.

Transfer to individual serving bowls or onto a large serving platter. Garnish with the parsley and serve immediately.