March 4th, 2016
In food processor, process hazelnuts and sugar for about 40 seconds, until finely ground. Scrape the bowl sides with a spatula. Add flours, baking powder, and salt and pulse to combine. Set aside.
Beat butter with an electric mixer on medium speed for about 1 ½ minutes, until light, fluffy, and smooth. Add maple sugar and beat until combined. Add egg and vanilla extract and beat until completely incorporated. Add hazelnut mixture and beat until just combined. Refrigerate dough for at least 20 minutes, or until firm.
While dough chills, place a rack in the center of the oven. Preheat oven to 350° F. Line two baking sheets with parchment paper.
Form 20 1-tablespoon scoops of dough into balls; refrigerate remaining dough. Arrange balls on a prepared baking sheet. Gently press the center of each with your thumb, creating a slight indent.
Bake, rotating the tray once halfway through, 10 to 12 minutes, until cookies are lightly golden. Repeat step 4 with remaining dough, forming about 15 more balls.
Allow cookies to cool before spooning a small dollop of maple butter into the center of each.
Note: Batter can be froze for up to 1 month.