Season the chicken: Pat the chicken dry. Rub with 1 tablespoon olive oil, 1 teaspoon salt, 1/2 teaspoon black pepper, and 1/2 teaspoon garlic powder. Add a pinch of red pepper flakes if you like heat.

Grill the chicken: Heat a grill or grill pan over medium-high. Cook 5–6 minutes per side, until the internal temperature reaches 165°F (74°C). Rest 5 minutes, then slice or cube.

Cook the pasta: Bring a large pot of salted water to a boil. Cook the pasta to al dente according to the package. Reserve 1/4 cup pasta water. Drain and rinse briefly under cool water to stop the cooking.

Toss with pesto base: In a large bowl, combine the warm pasta, 1/2 cup pesto, and a splash of reserved pasta water. Stir until the pasta is lightly coated. Add more pesto if needed for a glossy finish.

Add the mix-ins: Fold in the sliced grilled chicken, tomatoes, mozzarella, and red onion. Add olives and cucumber if using. Sprinkle in lemon zest and squeeze in 1–2 tablespoons lemon juice.

Adjust and season: Taste and add salt, pepper, and extra lemon as needed. If it looks dry, add a drizzle of olive oil or another spoonful of pesto.

Finish with greens and crunch: Gently fold in the spinach or arugula so it wilts slightly but stays vibrant. Top with toasted pine nuts for texture.

Serve your way: Enjoy immediately slightly warm, or chill for 30–60 minutes for a colder salad with more melded flavors.