Bring a pot of salted water to a boil and cook the whole grain penne according to package directions until al dente.
While the pasta cooks, reserve 3 tablespoons of the starchy pasta water, then drain the rest.
Season the chicken breast with garlic powder, sea salt, and black pepper.
Heat the olive oil in a skillet over medium-high heat and sauté the chicken until golden brown and cooked through, about 5-6 minutes per side.
Remove the chicken from the pan to rest, then slice into thin strips.
In the same skillet, lower the heat and add the minced garlic, sautéing for 1 minute until fragrant.
Add the fresh baby spinach to the skillet and cook until just wilted.
In a small bowl, whisk together the Greek yogurt, grated parmesan, and the reserved pasta water to create a smooth sauce.
Add the cooked pasta and sliced chicken back into the skillet.
Pour the yogurt sauce over the pasta and chicken, tossing gently over low heat until the sauce is creamy and coats every noodle.