Ingredients

• 1-1/4 cups (150 grams) buckwheat flour
• 1-1/2 cups (204 grams) all-purpose flour
• 1-1/2 sticks (12 tbsp, 170 grams) unsalted butter, cut into chunks, at room temperature
• 3/4 cup (150 grams) sugar
• 1/2 tsp fine sea salt
• 1 large egg, at room temperature
• 4 ounces (113 grams) bittersweet, semisweet or milk chocolate, finely chopped

Method

1. Center a rack in the oven and preheat the oven to 350 degrees F. Line a baking sheet with parchment paper of a silicone baking mat.
2. Spread the buckwheat flour out on the baking sheet, leaving a border of a few inches bare. Toast the flour for 5 minutes, then stir it with a table knife or a heatproof spatula. Continue to toast the flour, stirring every 5 minutes, for another 15-20 minutes. The flour is ready when it is a darker shade of beige and fragrant; it might even smoke around the edges. Let it cool to room temperature. Turn off the oven; you won't need it for a while.
3. Measure a cup of the cooled buckwheat flour into a medium bowl and add the all-purpose flour; whisk to blend.
4. Working in the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the butter at medium speed until it is soft and creamy. Add the sugar and salt and beat for another 2 minutes, or until the mixture is again smooth and creamy. Add the egg and beat for 1 minute more. The mixture may curdle; if it does, beat for another few seconds, and it that doesn't undo the curdling, adding the dry ingredients will. Reduce the mixer speed to low and add the flours in 2 or 3 additions, mixing until they disappear into the dough. Add the chopped chocolate and pulse the mixer on and off several times to incorporate it. Or, if you'd prefer, use a flexible spatula to stir the chocolate into the dough.
5. Turn the dough out onto a work surface and knead it gently, just so that it comes together. Divide the dough in half.
6. Working with half of the dough at a time, put the dough between two sheets of parchment or wax paper and roll until it is 1/4 inch thick. (Check for thickness, not shape.) Slide the dough, still between the papers, onto a cutting board or cookie sheet. Slide the second piece of dough on top of the first and put the dough in the freezer to firm for about 1 hour. Alternatively, you can refrigerate the dough for several hours (or for up to two days).
7. When you are ready to bake: Position the racks to divide the oven into thirds and preheat the oven to 350 degrees F. Line two baking sheets with parchment paper or silicone mats.
8. I like to use to a 1-3/4 inch round cutter for the cookies, but you can use whatever you like, knowing that your yield and perhaps your baking time will change depending on the size of your cutter. Cut out as many cookies as you can from the first piece of dough and put them on a baking sheet, leaving an inch or so between. Keep the cookies in the fridge or in a cook spot while you cut cookies from the second piece of dough. Combine the scraps, put them between two sheets of parchment or wax paper and roll out until it is 1/4 inch thick; chill before cutting and baking.
9. Bake the cookies for 13-15 minutes, rotating the sheets from top to bottom and front to back at the midway point. Remove the baking sheets from the oven and let the cookies rest on the sheets for a few minutes, then transfer them to rack to cool to room temperature.

Notes