Bring a large pot of salted water to a boil and cook the whole wheat penne according to package directions until al dente.
Before draining the pasta, reserve 1 tablespoon of the starchy pasta water and set it aside.
While the pasta cooks, dice the chicken breast into bite-sized pieces and season evenly with sea salt, black pepper, and garlic powder.
Heat the olive oil in a large skillet over medium-high heat. Add the chicken and sauté for 5-7 minutes until golden brown and cooked through.
Lower the heat to medium and stir in the chopped sun-dried tomatoes and baby spinach, cooking just until the spinach begins to wilt.
In a small bowl, whisk together the basil pesto, Greek yogurt, and reserved pasta water until a smooth, creamy sauce forms.
Add the cooked pasta to the skillet with the chicken and vegetables, then pour the pesto sauce over the top.
Toss everything together gently over low heat for 1 minute until the pasta is thoroughly coated and the sauce is warm.