Generously grease and flour a 12-cup Bundt pan; set aside.
Beat butter at medium speed with an electric mixer about 2 minutes or until creamy. Gradually add granulated sugar, beating 5 to 7 minutes. Add eggs, 1 at a time, beating just until yellow disappears.
Combine flour, baking powder, and salt. Add to butter mixture alternately with 1 cup eggnog, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in vanilla and, if desired, brandy.
Pour half of batter into prepared pan. Stir cinnamon and next 3 ingredients into remaining batter. Spoon spice batter over plain batter. Swirl batters together, using a knife.
Bake at 350° for 50 to 55 minutes or until a long wooden pick inserted in center comes out clean. Cool in pan on a wire rack 15 minutes. Remove from pan; cool on wire rack.
Place cake on a cake plate; dust with powdered sugar.
Combine 1 cup powdered sugar and whipping cream, stirring until smooth. Drizzle glaze over cake. Yield: 16 servings.