Cream the sugars and butter in a large mixing bowl until light, pale and fluffy.
Add in the egg yolk and vanilla and beat until fully incorporated.
Sift in the flour in two batches and fold it in with a rubber spatula. Transfer the dough onto a large piece of plastic wrap (cling film). Spread the dough out into a large rectangle/square into 1/2-inch thick. Wrap it up with the plastic wrap and refrigerate till firm, at least 1 hour.
Preheat the oven to 160 degrees Celsius. Line a baking sheet with parchment paper.
Unwrap the dough and cut it into 1 1/2-inch by 1/2-inch rectangles. Pinch the rectangles slightly to form fingers. Stick a piece of almond flake in the front for he fingernail. Score the dough slightly with a small, sharp knife (look at your own finger as guidance ;)).
Place the cookie dough onto the baking sheet and bake for 10 to 13 minutes until lightly golden. The cookie will expand during baking. Cool the cookies completely on a wire rack and store in an air-tight container for up to 5 days.