Prepare some food grade acetate and cut it into even sized triangles, you will need 6, but make at least 12 to allow for breakages.Take something round like a buche mould that you can place the triangles in, so that they will curve as they dry.
Melt 100g chocolate in a bowl over a pan of simmering water until it reaches 45C. Remove the bowl from the heat, wipe the bottom of the bowl with a towel and add some of the reserved 100g chocolate, stirring regularly until all of the chocolate is melted, keep adding chopped chocolate until the temperature is reduced to 32C.
The chocolate is then tempered and ready to use, take the acetate triangles and pour a little of the chocolate on them, using an offset spatula, spread the chocolate in one direction and then leave it for a few seconds to set. Place the chocolate triangles in the buche mould and allow them to set overnight somewhere cool.
When you’re ready, peel the acetate gently off the chocolate triangles and store them in an airtight container until you are ready to use them.