Boil a pot of water and cook the whole wheat pasta according to package directions until al dente. Reserve 2 tablespoons of pasta water before draining.
While pasta cooks, mince the garlic and chop the chicken breast into bite-sized pieces.
Heat olive oil in a large skillet over medium heat. Add chicken, garlic, oregano, sea salt, and black pepper.
Sauté the chicken for 6-8 minutes until golden brown and cooked through.
In a small bowl, whisk together the Greek yogurt, lemon juice, and lemon zest until smooth.
Reduce skillet heat to low. Add the cooked pasta, reserved pasta water, and fresh spinach to the chicken.
Stir in the lemon-yogurt mixture, tossing constantly until the spinach is wilted and the sauce is creamy.
Remove from heat immediately to prevent the yogurt from curdling. Garnish with fresh parsley and serve warm.