Cook pasta according to package directions. Before draining, scoop out ½ cup of the pasta-cooking water and set aside. Drain the pasta and return it to the cooking pot to keep it warm
2
Meanwhile, in a large nonstick skillet over medium-low heat, combine the oil and garlic. Cook for about 2 minutes or until garlic is soft and fragrant. Do not brown. Add the tomato and cook for about 4 minutes longer, or until the tomato starts to soften. Add the spinach and cook, tossing for about 1 minutes more or until wilted. Stir in balsamic vinegar, olives, pepper. Reduce to low.
3
Add the tomato mixture to the reserved pasta and toss to coat. Add feta cheese. If needed, add a few TB of the reserved cooking water, if needed, to moisten the pasta.
