In a large pot, simmer the chicken with peppercorns, bay leaves, onion, garlic, parsley and water to cover until chicken is cooked and tender, about 1 to 2 hours depending on the size of the chicken. Remove chicken, strain and reserve the stock.
When chicken is cool, remove and discard skin, remove meat from bones and separate meat into bite-size or slightly larger pieces.
For the sauce, sauté chopped onion and garlic in butter until soft but not fully cooked.
In a food processor, puree onion and garlic mixture, bread, paprika, pepper, pecans and salt until smooth. With motor running, slowly add chicken stock to achieve a thick, creamy consistency.
Place the chicken pieces on a serving dish in layers and cover each layer with sauce.
For the garnish, warm olive oil in a sauce pan with the paprika and drizzle over the dish. Top with pecan halves.