Preheat oven to 400°F (200°C). Coat an oval baking dish or cast-iron skillet with 1 tbsp extra virgin olive oil.

Heat 1/2 tbsp olive oil in a pan over medium heat. Sauté minced garlic for 30 seconds until fragrant, then add chopped spinach and cook for 1-2 minutes until wilted. Remove from heat.

In a bowl, combine sautéed spinach, garlic, whole milk ricotta, half of the mozzarella cheese, salt, pepper, and optional feta cheese.

Pat chicken breasts dry with paper towels. Cut crosswise slits at 1/2-inch intervals into each breast, cutting about 80% through without slicing completely through.

Stuff each Hasselback slit generously with the spinach-ricotta mixture and a small piece of remaining mozzarella.

Transfer stuffed chicken breasts to prepared baking dish. Drizzle with remaining extra virgin olive oil and season evenly with smoked paprika, Italian seasoning, dried oregano, salt, and black pepper.

Bake uncovered for 20–25 minutes until internal temperature reaches 165°F (74°C) and cheese is bubbly and golden brown.

Remove from oven and let rest for 5–10 minutes. Garnish with chopped fresh parsley and basil before serving.