Bring a large pot of salted water to a boil and cook the whole grain penne according to package directions until al dente.
While pasta cooks, reserve 2 tablespoons of the starchy pasta water, then drain the rest.
Season the chicken breast with sea salt and black pepper on both sides.
Heat olive oil in a large skillet over medium-high heat. Add the chicken and sear for 5-6 minutes per side until golden and cooked through.
Remove chicken from the pan, let it rest for a few 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.
Turn the heat to low and whisk in the Greek yogurt, parmesan cheese, and the reserved pasta water to create a smooth sauce.
Add the baby spinach to the skillet and stir until just wilted.
Fold the cooked pasta and sliced chicken back into the skillet, tossing well to coat everything in the creamy sauce.
Garnish with fresh chopped parsley and serve immediately.