Preheat oven to 350 degrees Fahrenheit.
On medium heat, warm up a couple of generous tablespoons of olive oil in a large casserole dish. In batches (in order not to crowd the chicken), cook the chicken for about 2 to 3 minutes per side. Remove from dish.
Add 4 tablespoons of the butter, along with the chopped onion and chopped bell pepper. Lower the heat to low-medium and cook until the onions and bell pepper begin to soften.
Stir in the tomato paste, along with the paprika, chili pepper, cayenne pepper, salt, and pepper.
Add the chopped tomatoes, and cook until the tomatoes begin to soften.
Return the chicken to the pan.
Pour in the chicken stock, along with the dill and parsley. Raise the heat back to medium and cook for 10 to 15 addition minutes.
Stir in the rice, along with the additional butter.
Bake in the preheated oven for about 40 minutes, or until the chicken is fork tender and the rice is fully cooked and has soaked up most of the liquid.