Bring a large pot of salted water to a boil and cook the whole wheat penne according to package directions until al dente.
While the pasta cooks, reserve 0.25 cup of the starchy pasta water, then drain the noodles and set aside.
Season the chicken breast with half of the sea salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat and sear the chicken for 5-6 minutes per side until golden and cooked through.
Remove the chicken from the pan, let it rest for 3 minutes, then slice into thin strips.
In the same skillet, reduce heat to medium and add the minced garlic, sautéing for 1 minute until fragrant.
Add the baby spinach to the skillet and cook until just wilted.
In a small bowl, whisk together the Greek yogurt, parmesan cheese, and the reserved pasta water until smooth.
Turn off the heat and add the cooked pasta and sliced chicken back into the skillet.
Pour the yogurt mixture over the pasta, tossing quickly to coat everything in a creamy sauce without curdling the yogurt.
Garnish with fresh parsley and the remaining salt and pepper before serving.