In a large bowl, sift the flour and baking soda. Stir in the spices and salt (if using). Set aside.
In a mixing bowl, beat the butter and brown sugar with a hand mixer on medium speed for 2 minutes, until light and creamy, then add the molasses, egg and vanilla. Beat till combined.
Fold in the flour mixture. The dough will be thick and sticky, so chilling it is necessary. Cover the bowl with clingfilm and place in the fridge for at least 1 hour.
When ready to bake, preheat the oven to 175 C and line a baking tray with a silicone mat or non-stick baking paper.
Let the dough sit out at room temperature for 10 minutes, then roll into equal sized rounds. I made 14 large cookies, you can roll smaller dough balls and make more cookies.
Roll each dough ball in the granulated white sugar, then place on the baking tray.
Bake for 10 to 15 minutes, depending on how large your cookies are. Rotate the tray halfway through baking to ensure the cookies are evenly browned. They are done when the edges are lightly browned and firm and the tops are a little cracked, but still soft to touch. Allow to cool for 10 minutes on the tray, press down lightly if they’re very puffy, then transfer to a wire rack to cool completely. They will firm up as they cool. Enjoy!