Bring a large pot of salted water to a rolling boil. Add the pasta and cook until just al dente, about 8-10 minutes. Drain, reserving about a cup of pasta water, and set aside.
While the pasta cooks, heat the olive oil in a wide skillet over medium heat. Add the minced garlic and sauté for about 30 seconds until fragrant and golden, filling the kitchen with a warm aroma.
Add the chopped spinach to the skillet. Stir constantly until wilted and vibrant green, about 2 minutes. If it sticks or starts to burn, splash in a little reserved pasta water or olive oil.
Crumble the feta cheese into the skillet. Stir gently as it begins to melt and create a creamy, tangy sauce that coats the spinach and garlic evenly. If the sauce seems too thick, add a splash of reserved pasta water to loosen it up.
Reduce the heat to medium-low and add the drained pasta to the skillet. Toss everything together so the feta and spinach coat the pasta thoroughly, creating a silky, cheesy sauce. Squeeze in half a lemon for brightness, if using, and season with freshly cracked black pepper.
Taste the dish and adjust seasoning with more black pepper or salt if needed. Serve immediately, garnished with extra feta or lemon wedges if desired, and enjoy the warm, vibrant flavors.
