Pat the chicken dry and season both sides with salt, pepper, and dried oregano.
Heat olive oil in a skillet over medium-high heat. Add chicken and cook for about 5-6 minutes on each side until golden and cooked through (internal temperature should reach 165°F). Remove chicken and set aside.
In the same skillet, reduce heat to medium. Add minced garlic and sauté for about 30 seconds. Pour in white wine, add tomatoes, olives, and capers. Cook until tomatoes start to soften.
Return chicken to the skillet. Add spinach and cover for 2-3 minutes until spinach wilts. Adjust seasonings as needed.
Sprinkle feta cheese and fresh parsley over the top when serving.