Coca-Cola Chocolate Cake

I've had this recipe for probably 30 years. It's been awhile since I made it but it's nice and moist, wonderful flavor. Several already on this site but none with these exact ingredients. The icing is a bit thin if you follow directions, it's more like a glaze, so I think it needs maybe another cup of powdered sugar.

• Ready In: 55 mins
• Yields: 1 cake

Ingredients

• 2  cups sugar
• 2  cups flour
• 1⁄2 cup margarine
• 1⁄2 cup shortening
• 3  tablespoons  cocoa or 1  melted baking  chocolate square
• 1  cup  Coke
• 1⁄2 cup buttermilk
• 1  teaspoon vanilla
• 2  eggs, beaten
• 1 1⁄2 cups small marshmallows

• ICING

• 1⁄2 cup butter or 1⁄2 cup margarine
• 3  tablespoons  cocoa
• 1  cup pecans, chopped
• 6  tablespoons  Coke
• 1  lb powdered sugar

Directions

1. Sift flour and sugar together.
2. Combine the margarine, shortening, cocoa and cola in saucepan and bring to boil. Add the chocolate mixture to sugar-flour mixture. Add buttermilk, soda, vanilla and beaten eggs.
3. Beat well, fold in marshmallows.
4. Bake at 350°F for 40 minutes in a 13 x 9 pan.
5. Ice with the chocolate icing.