Preheat the oven to 360 F.

In an electric mixer bowl, using the paddle attachment, mix the egg yolks and sugar on medium speed until the mixture becomes a pale, yellow colour. Add the soft butter, little by little, and continue to mix to create a nice aeration. Use a rubber spatula to scrape the sides and bottom of the bowl to ensure the dough is smooth.

Stir the cake flour and baking soda together in another bowl. Reduce to low speed, add the flour and mix until combined.

Transfer the dough to a floured work surface and shape into a 1-inch (2.5-cm) thick rectangle. Wrap in plastic and refrigerate for 6 hours. Using a rolling pin, roll the dough to a thickness of ½-inch (1.25-cm). Cut into 2-inch rounds (5-cm) and place on a parchment-lined baking sheet.

Combine any dough scraps, roll out again and cut out shapes until all the dough is used. Using a fork, crisscross the top of each cookie to create a nice square pattern. Place the tray in the refrigerator and chill for 1 hour.

In a small bowl, whisk the egg. Using a pastry brush, apply egg-wash to the entire surface of each cookie. Sprinkle a small pinch of sea salt on each cookie.

Place the baking tray on the middle rack of the oven. Bake for 15 minutes, then rotate the tray 180 degrees and bake for another 10 minutes. You want the cookies to have a nice light golden ring on the outside, and a lighter colouring in the centre.

Because of the egg wash, the cookies brown faster, so keep a close watch.

For a twist, add 1 tablespoon (15 mL) of crushed fennel or lavender seeds to the dough during the mixing process to create a sable Breton with a floral hint. For this particular cookie, I love using a large crystal sea salt.