Bring a medium pot of salted water to a boil and cook the whole wheat penne according to package directions until al dente.
While pasta cooks, season the chicken breast with half of the sea salt, black pepper, and dried oregano.
Heat olive oil in a large skillet over medium-high heat. Add the chicken and sear for 5-6 minutes per side until golden brown and cooked through.
Remove chicken from the skillet and let it rest for 2 minutes before slicing into bite-sized strips.
In the same skillet, lower the heat to medium and add the minced garlic, sautéing for 30 seconds until fragrant.
Add the fresh spinach to the skillet and cook until just wilted, about 1 minute.
In a small bowl, whisk together the Greek yogurt, grated parmesan, and the remaining seasonings. Add 2 tablespoons of hot pasta water to the yogurt mixture to thin it into a sauce consistency.
Drain the pasta and add it to the skillet with the spinach. Turn off the heat.
Stir in the yogurt sauce and the sliced chicken, tossing everything together until the pasta is evenly coated and creamy.
Serve immediately while hot.