Preheat your oven to 325°F (165°C). This is crucial for even baking. While the oven warms up, prepare your baking pan by gently spraying a 9×13-inch pan with nonstick spray and lining it with parchment paper. This will prevent the cookies from sticking.
In a large mixing bowl, combine unsalted butter and powdered sugar using a fork or an electric mixer. Mix for 2 to 3 minutes until the mixture is smooth and creamy. You’ll know it’s ready when it’s light and fluffy, and the sugar is fully incorporated.
Add the vanilla extract and a pinch of salt to the butter mixture. Blend again until evenly mixed. The vanilla will add warmth to the cookies, enhancing their delightful essence.
Gradually add in the all-purpose flour. Start with one-third of the flour and mix until fully incorporated, then continue adding the remaining flour in batches. The dough should become thick and velvety, indicating that the ingredients are well combined.
Transfer the dough into the prepared baking pan. Use your hands to press the dough flat evenly, spreading it out to the corners. This step is important for uniform baking.
For an extra smooth surface, place another sheet of parchment paper over the dough and gently roll over it with a small rolling pin or a flat-bottomed glass. This will ensure the cookies bake evenly and have a beautiful finish.
Now, remove the top layer of parchment paper. Place the pan in the preheated oven and bake the shortbread for 20 minutes until the edges turn lightly golden. Keep an eye on them to prevent overbaking.
After 20 minutes, take the pan out of the oven, but keep the oven hot. Using a sharp knife, carefully make cuts in the dough. Create 5 cuts parallel to the length of the pan, dividing it into 6 equal strips. Then, make 2 cuts parallel to the width to create 18 pieces in total.
With the back of a fork, gently press down on each piece, creating two parallel lines of holes. This step is traditional for Walkers Shortbread Cookies and allows for even baking and a classic look.
Return the pan to the oven and bake for an additional 8 to 9 minutes. The cookies should be lightly golden and fragrant. Once done, remove the pan and allow the cookies to cool completely in the pan before enjoying.