Baking Tips & Tricks Prep How to Cut a Cake with Floss Back to Prep Prep How to Cut a Cake with Floss If you've only got the one cake tin and have baked your sponge, you might be left wondering how you're going to split it. We have a quick tutorial that shows you the quickest and easiest way to do this. For a basic sponge recipe, click here Method Take dental floss and wrap it equally around the cake. Hold it tight with both hands and pull in opposite directions so it cuts through the middle of the cake and leaves you with two perfectly even layers.