Preheat oven to 350F. Grease and lightly flour 3 (9-inch) cake pans.
Sift together flour, salt, baking powder and baking soda. Cream butter and sugar until light and fluffly. Add eggs one at time; beat well after each addition. Add melted chocolate liqueur; blend well. Mix together milk and water. Add dry ingredients to chocolate mixture alternately with milk mixture. Mix until smooth. Stir in cooking oil. Pour into pans.
Bake until tops spring back when lightly touched with finger, about 30 minutes. Let layers cool in pans about 5 minutes; turn out onto wire racks. Let cool completely. Fill and frost with Chocolate Orange Frosting and garnish with nuts.
To make frosting: Beat cream cheese until fluffy. Beat in orange chocolate liqueur and orange extract until well blended. Gradually beat in sugar until smooth. Add grated peel; mix well.