Idaho Potato Cake
["1 c. margarine, softened", "2 c. sugar", "2 eggs", "1 c. cold, mashed potatoes", "1 Tbsp. vanilla", "2 c. all-purpose flour", "1/4 c. cocoa", "1 tsp. soda", "1 c. milk", "1 c. chopped nuts (optional)"]
["In a mixing bowl, cream margarine and sugar until fluffy.", "Add eggs, one at a time, beating well after each addition.", "Blend in potatoes and vanilla."]
["margarine", "sugar", "eggs", "cold", "vanilla", "flour", "cocoa", "soda", "milk", "nuts"]