1. Preheat the oven to 190 ºC, 10 minutes before baking biscuits. Lightly oil 3 baking sheets.
2. Divide butter and sugar between 2 mixing bowls and cream together until light and creamy.
3. Beat 1 egg into each bowl. Then stir 200 g flour and the cocoa into the first bowl, and mix to a soft dough. Wrap and chill for 30 minutes.
4. Add remaining flour and vanilla essence to the second bowl, mix to a dough, wrap and chill for 30 minutes. Shape biscuits, using instructions below, then chill again for 30 minutes. Bake for 8 to 10 minutes. Cool for 1 minute, then transfer onto a wire rack.
PINWHEELS: Roll out an equal amount of both doughs to form 2 oblong strips. Place chocolate dough on top of vanilla dough and roll up like a Swiss roll. Slice, then place slices on a baking sheet. Chill, then bake.
CHEQUERBOARDS: Roll out an equal amount of both the doughs to form two oblong strips. Halve each oblong lengthways. Place 1 vanilla and 1 chocolate length side by side, then the remaining chocolate length on top of the first vanilla and vice versa. Press together. Slice thinly, place on baking sheets. Chill then bake.
GARLANDS: For each biscuit, form 8 small balls with vanilla dough. Place in a circle on baking sheet, with sliced cherries in joins. Dredge with castor sugar, chill then bake.
CHOCOLATE DODGERS: Roll out chocolate dough to 6 mm thickness. Using a 5 cm plain cutter, cut out an even number of rounds. Place on a baking sheet, chill then bake. When cold, sandwich with butter cream. Dredge with icing sugar.
CHOCOLATE TWISTS: Roll out vanilla dough to form an oblong strip 6 mm thick. Cut smaller strips 6 mm wide. Twist 2 strips together, place on a baking sheet. Dredge twists with castor sugar, chill then bake. When cold, dip the ends in melted chocolate.