Place softened butter and the sugar in a bowl. The soft butter makes it really easy to cream a small batch using just a wooden spoon. If short on time, leave the butter in the paper wrapper and zap it in the microwave for a few seconds. Be careful, the butter should be soft, not melted.
Use a wooden spoon or a spatula to mix the sugar and butter together until you get a nice smooth consistency. I use a wooden spoon to stir and smash it all together and finish mixing with a spatula. You can use an electric mixer, but when working with such a small amount I just cream the butter by hand.
Next, mix in the egg white. it’s fine if a little yolk gets into the dough.
Add the flour 1/4 cup at a time. A dough whisk makes this easy to mix.
Place the dough on a pastry board or parchment paper and form it into a ball.
Press the dough into a disc snap and wrap in plastic wrap. refrigerate the dough to chill for about an hour.
Use a rolling pin to roll out the dough to about 1/4 inch thickness.
Cut the shortbread cookies into the desired shape. I used my #55 Matfer cutter, but you can also use a knife to cut into a rectangular or even wedge shape.
Use a thin spatula to loosen the cookies and transfer them to a parchment-lined baking or cookie sheet. Place in the refrigerator for 15-20 minutes before baking.
Bake the shortbread cookies at 350° F for 15-18 minutes. The cookies should be light brown. Cool completely before serving.
Notes
Since French shortbread cookies have a simple and delicate flavor, it's important to use high-quality ingredients. Use unsalted butter, preferably European-style, for its rich and creamy texture. Use fresh, good-quality flour and granulated sugar.
Ensure the butter is at the right temperature. It should be cool to the touch but still pliable. Softened butter makes it easier to cream with the sugar and creates a smooth cookie dough.
Cream the butter and sugar together until light and fluffy. This step incorporates air into the dough, resulting in a lighter texture for the cookies.
Sift dry ingredients: Sift the flour and salt together before adding them to the butter mixture. This helps remove any lumps and ensures even distribution of the dry ingredients in the dough.
Stop mixing as soon as the dough comes together and no streaks of flour remain.
Wrap the cookie dough in plastic wrap and refrigerate it for at least 1 hour, or even overnight if possible. Chilling the dough allows the butter to solidify, making it easier to handle and shape. It also helps the cookies hold their shape while baking.
Preheat the oven to the recommended temperature stated in the recipe. Place the cookies on a parchment-lined baking sheet, leaving some space between them for spreading. French shortbread cookies should remain pale in color.