Bring a pot of salted water to a boil and cook the whole wheat penne according to package directions until al dente.
Reserve 0.25 cup of the starchy pasta water before draining the noodles.
While the pasta cooks, dice the chicken breast into bite-sized pieces and season with sea salt, black pepper, and dried oregano.
Heat the olive oil in a large skillet over medium-high heat and sauté the chicken until golden brown and cooked through, about 5-7 minutes.
Add the minced garlic and fresh baby spinach to the skillet, sautéing for 1 minute until the spinach is just wilted.
In a small bowl, whisk together the Greek yogurt, grated parmesan cheese, and the reserved pasta water until smooth.
Reduce the skillet heat to low and add the drained pasta and the yogurt mixture to the chicken and vegetables.
Toss everything together gently until the pasta is coated in a creamy sauce, being careful not to let the yogurt boil to prevent curdling.
Serve immediately while warm and creamy and delicious.