Bring a large pot of salted water to a boil. Add the whole wheat rotini and cook until al dente, approximately 10 minutes. Remember to reserve ½ cup of pasta water before draining.

In a large pot or skillet, heat olive oil over medium heat. Add the diced chicken breasts, cooking for 2-3 minutes until browned. Season with salt and pepper.

Stir in the diced tomatoes, zucchini, red onion, and minced garlic into the chicken. Continue to sauté for about 5 minutes, until the vegetables become tender but still slightly crisp.

Return the cooked rotini to the pot filled with the sautéed mixture. Mix in the reserved pasta water and jarred pesto, stirring until every piece of pasta is beautifully coated.

Gently fold in the chopped spinach until it just wilts, then remove the pan from the heat. Serve immediately.