Heat oven to 350°. Butter and flour a 10-cup Bundt pan. In a large mixing bowl, combine flour, sugar, 1 tablespoon of grated orange peel, baking soda, allspice, nutmeg, vegetable oil, eggs, orange juice, and chocolate. With mixer at low speed, beat just until blended. Increase speed to medium and beat 2 minutes longer. Stir in grated carrots, raisins, and walnuts. Pour batter into prepared pan. Bake at 350° for 45 minutes, or until a wooden pick or cake tester inserted in center comes out clean. Cool completely on rack. Dust with powdered sugar or drizzle with Cream Cheese Glaze, below.
Combine all ingredients in a small bowl. Stir until smooth, adding a little more milk or powdered sugar, if necessary.