Cook spaghetti according to package directions. Reserve ¼ cup of pasta water and drain the remaining water. Add 1 tablespoon of olive oil to the pasta, toss and set aside.
Add 1 tablespoon olive oil to a large skillet over medium high heat. Saute the diced onions until soft.
Add garlic to the pan and saute for 1 minute.
Add cherry tomatoes to the pan with the remaining olive oil and saute for several minutes, until the tomatoes are softened.
Add the baby spinach to the pan and cook until wilted.
Add the kalamata olives, lemon juice, red wine vinegar, dried oregano, kosher salt, and black pepper to the pan and cook for 1 minute.
Remove from heat and add the cooked spaghetti. Toss to coat in the vegetable mixture.
Add the crumbled feta cheese and fresh sliced basil and toss one more time to combine.
Garnish with additional fresh chopped basil or parsley and serve, enjoy!