Pre-heat the oven to 190°C (375°F). Line two large trays with baking paper.
Beat the butter and sugars together until light and fluffy. Add the egg, mix, and then the syrup (molasses).
In a separate bowl mix the remaining dry ingredients together. Add to the wet ingredients and work until everything is combined and a very sticky dough is formed.
Using either a spoon or your hands, scoop up balls of dough (remember, the dough is supposed to be sticky, so if using your hands, you won't be able to form a perfect ball). I made both large (1.5 tablespoons) and smaller cookies to experiment, so how big you would like them is up to you (baking times will need to be adjusted accordingly though).
Drop the cookie mixture on to the prepared trays with tons of space in between (they are prolific spreaders). Bake from between 10-13 minutes depending on their size. The cookies puff up a little, but drop back down to make fairly flat cookies and I noticed that the larger cookies became flatter than the smaller.
Allow cookies to cool for a while before transferring to a wire rack. Let them cool completely before filling.
For the filling, follow the instructions for my carrot cake (link in notes)
To assemble: take two cookies of similar size and turn one upside down so the flattest part is facing you. Pipe or spread the frosting over and then place the other cookie on top. Sprinkle with a little icing sugar and enjoy!