In a bowl, combine Greek yogurt, minced garlic, oregano, paprika, salt, and pepper to create a flavorful marinade. Add chicken breast pieces, ensuring they are fully coated, and cover the bowl. Allow the chicken to marinate for at least 30 minutes in the refrigerator.

Heat a skillet over medium-high heat and drizzle with olive oil. Once shimmering, add the marinated chicken pieces and cook for 10-15 minutes until golden brown and cooked through. Let the chicken rest before slicing.

In a large mixing bowl, layer romaine and spinach. Top with sliced cooked chicken, fresh berries, pecans, and crumbled feta. Drizzle with dressing and toss gently until combined.