Add the ground meat to the saucepan and cook, stirring and breaking it up with a wooden spoon, until no pink remains, about 3 minutes. Stir in the rice, cinnamon, 1 1/2 teaspoons of salt, 1/4 teaspoon of pepper, three-fourths of the toasted nuts and the remaining 1/2 teaspoon of allspice. Add 2 1/2 cups of the chicken stock and bring to a boil. Cover the rice and cook over low heat for 10 minutes. Stir, then cover and continue cooking until the stock has been absorbed and the rice is tender, about 5 minutes longer. Remove the rice from the heat and let stand, covered, for 10 minutes. Fluff with a fork, transfer to a large bowl and sprinkle the remaining toasted nuts on top.