Bring a large pot of salted water to a boil.

Add spaghetti to the boiling water and cook according to package instructions until al dente.

While the spaghetti is cooking, heat olive oil in a large saucepan over medium heat.

Add diced onion and sauté until softened.

Add chopped garlic and sun-dried tomatoes and continue to sauté for another minute until fragrant.

Stir in halved green olives.

Pour in tomato and basil pasta sauce and add 1/2 cup of water.

Bring the sauce to a boil, then reduce heat and simmer for 3 minutes, stirring occasionally. Season to taste with salt and pepper.

Drain the cooked spaghetti well.

Add the drained spaghetti to the saucepan with the sauce and toss to coat evenly.

Divide the spaghetti among serving plates.

Sprinkle crumbled feta cheese over each serving.

Garnish with fresh basil leaves and serve immediately.