'- 280 gram (~ 2 cups) all-purpose flour- 3/4 teaspoon salt- 1 teaspoon baking powder- 1 teaspoon baking soda- 150 gram (~ 1 cup) walnut, toasted and coarsely chopped (I pulse for 2-3 seconds with my food processor)- 50 gram (~ 1/3 cup) sesame seeds, toasted- 175 gram (~ 12 tablespoons) unsalted butter, room temperature- 90 gram (~ 1/2 cup) sugar- 3 egg yolks- 1 egg, lightly beaten (for egg wash)

1. Preheat oven to 165 Celsius (325 Fahrenheit). Line two half-sheet pans with parchment paper and set aside.2. Whisk together all-purpose flour, salt, baking powder, and baking soda. Then add the walnut and sesame seeds and mix well. Set aside.3. In a mixing bowl, beat butter and sugar until light and fluffy, then add egg yolks and beat until well mixed. Then, lower the speed and gradually add the flour and walnut mixture and mix until it form a smooth cookie dough.4. NOTE: The texture of this cookie dough can be quite dry, and it is usually easier to work with hands at the very end to gather the dough.5. Form round balls (each about 1 teaspoon, or 10 gram) from the cookie dough and arrange on the prepared half-sheet pans. You should get about 80 balls, and you can arrange them in a 5x8 cookies per half-sheet pan.6. Use a fork and press each ball of cookie to create an indentation. Then brush the top of each cookie with the lightly beaten egg (egg wash).7. Bake in the preheated oven for 25-30 minutes, or until golden brown.8. Remove cookies from oven and rest in the baking sheets for 5 minutes, then transfer to a wire rack to cool completely. Store cookies in an airtight container.