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If you're not adding piped decorations but still want to add some flair, use a spatula to create waves in the icing. Swirl the whipped cream frosting to create small waves all over the cake for a more rustic look. For a crisp, uniform layer of frosting that's perfect for layering piped designs, run a bench scraper all around your cake. Start by working the bench scraper in a circle around the edges, before running it along the top. Pull the bench scraper towards you, and remove any excess frosting that collects on the blade. Once you've spread an even layer of frosting onto your cake, remove your icing bag from the fridge, and add some piped designs. Pipe around the edges of the cake to make a border, and pipe along the top to create flowers or pretty dollops. Practice piping a few designs on wax paper before icing directly onto the cake. Before serving, allow your cake to set in the fridge for at least 30 minutes so that your decorations will hold their shape. The icing will maintain its shape for 2-3 days if left in the fridge, and for several hours if left at room temperature. If you leave whipped cream frosting at room temperature for longer than 3-4 hours, it may become destabilized. It will lose its fluffy, frosting shape, and it might melt off your cake.

Summary:
Create a rustic look by making waves in the icing. Use a bench scraper to level the cake before piping decorations. Add piped decorations to your cake. Place the decorated cake in the refrigerator.