Hazelnut Cookies With Milk Chocolate
Make the Dough: Adjust oven rack to middle position and preheat to 350°F (180°C). In the bowl of a food processor, grind hazelnuts to form a smooth and creamy paste. Combine hazelnut paste, butter, sugar, salt, baking powder, baking soda, nutmeg, and vanilla in the bowl of a stand mixer fitted with a paddle attachment. Mix on low to moisten, then increase to medium and beat until light and fluffy, about 5 minutes. With mixer running, add egg and continue beating only until smooth. Reduce speed to low, add flour all at once, and mix to form a stiff dough. If not tempering the chocolate, fold chopped pieces into the dough now.