Preheat your oven to 200°C (400°F). Place the lemon halves cut-side up on a small baking tray, drizzle with a little olive oil, and roast for 15 minutes until softened and lightly caramelized.

Heat 1 tablespoon olive oil in a skillet over medium heat. Add garlic and cook for 30 seconds, then add spinach and cook for 2-3 minutes until wilted. Season with a pinch of salt and pepper, transfer to a bowl and let cool slightly.

Once cooled, squeeze out excess moisture from the spinach and mix with crumbled feta, oregano, and red pepper flakes.

Cut a deep horizontal pocket into each chicken breast, being careful not to cut all the way through. Season the chicken inside and out with salt and pepper.

Stuff each chicken breast with the spinach and feta mixture, then secure with toothpicks if needed.

Heat remaining 1 tablespoon olive oil in an oven-safe skillet over medium-high heat. Sear the stuffed chicken breasts for 3-4 minutes per side until golden brown.

Transfer the skillet to the preheated oven and bake for 18-22 minutes, or until the internal temperature reaches 74°C (165°F) when measured with a meat thermometer.

While chicken rests, squeeze the juice from the roasted lemon halves into a small saucepan. Add softened butter and whisk over low heat until melted and combined.

Remove toothpicks from chicken, drizzle with roasted lemon butter, and garnish with fresh parsley before serving.