In a small bowl, put the finely chopped sun-dried tomatoes with the Kalamata olives, the capers, crumbled Feta, the butter and freshly ground pepper.
Put the chicken on a cutting board and stuff it with the sun-dried tomato mixture, and then tie the chicken using cooking twine, starting from the back, over the top between the legs and breast, finishing at the legs and tie it tightly, and put the chicken in a deep Pyrex dish.
Heat up a deep non-stick skillet on high heat and then add the 2 tbsp olive oil and the 2 tbsp butter.
Saute the onion with the garlic and the leek for 2-3 minutes, stirring constantly to soften but not brown.
Add the tomato paste with the baby potatoes, continuing to saute for another 1-2 minutes, and then add the peas, crushed tomatoes, chicken broth, salt and freshly ground pepper, stirring well and then bring to a boil.
Spoon the mixture with the peas around the chicken in the Pyrex dish, cover with parchment paper and roast in a preheated oven at 180ο C for 1½ hours, removing the parchment paper in the last 30 minutes, so the chicken gets a nice brown color.
Once the chicken in ready, remove it from the oven and serve on a large platter in the center of the table.