Preheat oven to 375 °F (190 °C).

Using a sharp knife, butterfly each chicken breast (slice horizontally without cutting through) and open flat.

Season inside and out with salt, pepper, garlic powder, and oregano.

In a small bowl, toss together spinach, feta, sun‑dried tomatoes, garlic, and olive oil.

Divide filling evenly over each breast, then roll up tightly and secure with toothpicks or kitchen twine.

Place rolls seam-side down in a lightly greased baking dish.

Bake for 25–30 minutes, or until chicken is cooked through (165 °F / 75 °C internal).

Remove toothpicks before slicing. Let rest 5 minutes, then serve warm.