Start by cleaning and deboning your whole chicken, ensuring it is as flat as possible. If needed, use a meat mallet to gently pound the chicken to an even thickness.
In a large skillet, heat a drizzle of olive oil over medium heat. Add the finely chopped onion and sauté until translucent. Then, add the washed and roughly chopped spinach, cooking until wilted. Season with salt and pepper to taste and remove from heat.
In a mixing bowl, combine the sautéed spinach and onion mixture with the finely chopped dill, mint, parsley, and fresh green onion. Crumble the feta cheese into the mixture and stir until all the ingredients are well combined.
Lay the deboned chicken skin-side down on a clean surface. Spread the filling mixture evenly over the chicken, leaving a small border around the edges.
Starting from one end, carefully roll the chicken up tightly. Use the cooking twine to tie the roulade securely at several intervals.
Preheat your oven to 375°F (190°C). Place the roulade in a baking dish and drizzle with olive oil, seasoning the outside with salt and pepper. Bake for approximately 45-60 minutes, or until the chicken reaches an internal temperature of 165°F (75°C).
Once baked, remove the roulade from the oven and let it rest for about 10 minutes. This allows the juices to redistribute. When ready, slice into rounds and serve.
