In a medium bowl, beat butter and dark brown soft sugar with an electric mixer on medium speed until light and fluffy. Beat in lemon zest, lemon extract and vanilla.
Add flour and salt to butter/sugar mixture and blend well. With a rolling pin on a lightly floured surface, roll out dough 5mm thick. Cut out shortbread using a 5cm round pastry cutter and place 5cm apart on ungreased baking trays. Reroll scraps and repeat.
Bake 20 to 25 minutes, until cookies are pale golden, not brown. Let stand 2 minutes. Remove to a rack and let cool completely.
I followed this recipe, using dark brown soft sugar as stated, so not sure how to have them coming out "pale golden, not brown" the dough was already dark brown, they came out very dark and had the texture and taste of brandy snap.. very nice but not what I was expecting - 13 Apr 2015