Preheat the oven to 325ºF (160ºC). Place the white sugar in a small container or bowl and have two baking sheets ready.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, brown sugar, vanilla, and salt on medium-high speed until well combined, about 4 to 5 minutes, scraping down the sides of the bowl halfway.
With the mixer running on low, begin to add the flour gradually, a couple of tablespoons at a time. Wait until each addition of flour is mixed in before adding more. Stop the mixer and scrape down the paddle if the dough starts to clump around it. As more flour is added, the cookie dough may seem dry, however, it will eventually become smooth.
Once all of the flour is added, and the dough has pretty much cleared the sides of the bowl, stop the mixer. Dump the cookie dough out onto a work surface and knead it 15 to 20 times to ensure the flour is evenly distributed with the brown sugar and butter.
Divide the dough into approximately 24 x 25 gram portions (there will be enough leftover dough to make approximately another 1 ½cookies or one larger cookie if you want). Roll a cookie dough portion between your hands and shape it into a smooth ball with your fingertips. Place the ball of dough in the container of white sugar. Swirl the dough ball gently inside the container to completely coat it in sugar. Repeat this process for all of the cookie dough balls, placing them on the prepared baking sheet(s) as you go, 12 balls per sheet.
Stamp the top of each sugar-coated dough ball, directly on the baking sheet, with an approximately 2-¼ inch (5-½ cm) cookie stamp (see notes). Press the stamp straight down, gently but firmly, and flatten the dough balls to the edge of the stamp until the edges of the cookies just start to crack.
Once all of the cookies are stamped, place the two baking sheets in the preheated oven and bake the cookies for 22 to 24 minutes, rotating the pans halfway through. The cookies are done when the edges are lightly golden. Remove the sheets from the oven and place them on a wire rack to cool.
If you don't own cookie stamps simple flatten the dough balls with the bottom of a drinking glass.This recipe doubles well.Use salted butter because it tastes better.This is a dry dough, traditionally made by hand. If you don't have a mixer, and want to make the recipe by hand, it may seem like the last of the flour won’t mix in, but trust me, it will eventually become supple and smooth!Because the dough is fairly dry it holds the imprint of the cookie stamp and doesn't spread too much.Cracking along the edges of the brown sugar shortbread cookies when stamping is a sign you have the correct butter to flour ratio.This dough really isn't meant for rolling and using cookie cutters. For a delicious rolled-cookie option, try these lavender sugar cookies with Earl Grey glaze.Because of the amount of butter in this recipe, you don’t have to bake the cookies on parchment paper, however you can if you want to.Do not stamp beyond the edge of the cookie stamp. The cookies will flatten too much which risks the edges sticking to one another if they spread a bit in the oven.It is important to add the flour gradually. It must be mixed well and evenly or else some of the dough will be too buttery, and some of the dough will be too dry and floury.Kept in an airtight container or zip-top plastic bag, brown sugar shortbread will keep for over a week at room temperature, and up to three months in the freezer. They don't take long to defrost and are a pretty and festive treat to serve company with a cup of hot tea or eggnog.In a small box or bag tied with pretty ribbon stamped brown sugar shortbreads make a beautiful holiday gift!
You could try substituting ½ cup (75 g) of the all-purpose flour with rice flour. Many people claim this makes for a crispier brown sugar shortbread cookie.