Take the parchment paper large enough to have at least 2-inch excess on all sides of the baking pan.
I used lemon juice to make a plain sponge cake. You may substitute the 1½ tablespoons lemon juice with liquid coffee for mocha flavor, pandan juice for pandan flavor, beet juice for a red velvet decorated cake roll.
You may substitute 1 tablespoon cocoa powder with matcha, coffee, green tea or food color of your choice to create the patterns.
* Drawing the pattern:
If you are great at drawing, you can free hand and pipe the design directly on the parchment paper. For others, it may be easier to make a template first. Take a piece of paper as big as your baking pan so the paper fits well in the pan. Pencil your design first so you can erase if need to. Once you are happy with the pattern trace it with a marker so that the design will show through easily. Use the pattern sheet as your template and put the parchment paper for the cake on top of the template to draw the design with pastry tip.
*How to roll cake:
After removing the cake from the oven, cool a little. While the cake is still warm, roll the cake and parchment together. The parchment will end up coiled inside the cake. Cool the cake on a wire rack. After an hour or so when cake is completely cool, unroll and remove the parchment. The cake will be slightly wavy. Proceed with spreading the filling. Re-roll.
*Tips to handle piping bag:
Place the piping bag in a tall cup for filling so you won't have to hold while stuffing the bag.
Pipe out a small line on some extra paper to work out any air bubbles.
Filling the piping bag loosely will result in lots of air bubbles and the outcome sloppy and scribbled writing.