Line a large sheet pan with baking paper.
Unwrap the cookie dough log and leave it to rest on the plastic wrap.
Using a brush to lightly brush the cookie dough with egg wash.
Place a generous amount of demerera sugar on a baking sheet or plate which is big enough to hold the cookie dough log.
Roll the cookie dough in the sugar until it is evenly coated.
Using a sharp knife, slice the cookies from the log, about 1 cm (1/2 inch) thick.
Occasionally, your knife will hit a piece of chocolate, making it difficult to slice neat rounds. If your cookie slices fall apart, simply squish them back into shape.
Place the cookies on the sheet pan, spaced about 2 cm (1 inch) apart.