Hazelnut Cookies with Milk Chocolate

Ingredients

• 7 ounces whole hazelnuts, toasted and skinned
• 4 ounces unsalted butter, pliable but cool, about 60°F
• 10 1/2 ounces plain or lightly toasted sugar
• 1 1/2 teaspoons Diamond Crystal kosher salt; for table salt, use about half as much by volume or the same weight
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/8 teaspoon freshly grated nutmeg
• 1/2 ounce vanilla extract
• 1 large egg, straight from the fridge
• 9 ounces all-purpose flour, such as Gold Medal
• 6 ounces dark or milk chocolate, not chips, tempered

Directions

1. Set an oven rack in the center and heat the oven to 350 degrees F (180 degrees C). In a food processor, run the hazelnuts until they become a smooth, creamy paste. Add the hazelnut paste, butter, sugar, salt, baking powder, baking soda, nutmeg, and vanilla to the bowl of a stand mixer with the paddle attached. Start on low until the mixture is evenly moistened, then raise the speed to medium and beat until pale and fluffy, about 5 minutes. With the mixer still going, add the egg and beat just until the mixture looks smooth. Turn the speed back to low, add the flour in one addition, and mix until a firm dough forms. If you are not tempering the chocolate, fold the chopped chocolate into the dough now.
2. Divide the dough into 2-tablespoon portions, then roll each portion into a smooth ball. The portioned dough can be packed in a heavy-duty zipper-lock bag and refrigerated up to 1 week, or frozen up to 6 months. Bring it to room temperature until quite soft, about 70 degrees F or 21 degrees C, before continuing.
3. Place the dough balls on a parchment-lined half sheet pan, spacing them 2 inches apart to allow for spreading. Bake until the cookies are puffed, lightly golden at the edges, and still steamy in the centers, about 12 minutes. Leave them on the baking sheet until the crumb firms up, about 5 minutes.
4. When the cookies are fully cooled to room temperature, drizzle them with tempered milk chocolate. After the chocolate sets, move the cookies to an airtight container, separating layers with wax or parchment paper, and store at room temperature for up to 1 week.