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, slice 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, then add the chicken and cook until golden brown and cooked through, about 6-8 minutes.
Add the minced garlic and halved cherry tomatoes to the skillet, sautéing for 2 minutes until the tomatoes begin to soften.
Stir in the fresh spinach and cook until just wilted, then reduce the heat to low.
Reserve 2 tablespoons of pasta water, then drain the pasta and add it to the skillet.
Remove the skillet from the heat and stir in the Greek yogurt, parmesan cheese, and reserved pasta water until a creamy sauce forms.
Garnish with fresh parsley and serve immediately.