Preheat your oven to 400°F (200°C).
Cut the chicken breast into 1-inch bite-sized pieces to ensure even cooking.
In a medium-sized baking dish, arrange the chicken pieces, cherry tomatoes, and Kalamata olives in a single layer.
Place the block of feta cheese in the center of the dish, nestling it among the chicken and vegetables.
Drizzle the extra virgin olive oil over the chicken, tomatoes, olives, and feta.
Evenly sprinkle the dried oregano, garlic powder, sea salt, and black pepper over all the ingredients.
Bake for 20 to 25 minutes, or until the chicken is cooked through and the tomatoes have begun to burst.
Remove the dish from the oven and use a fork to gently mash the softened feta, stirring it into the pan juices to create a creamy sauce.
Place the fresh spinach in a serving bowl and top with the warm chicken and feta mixture, allowing the heat to slightly wilt the greens.