Preheat oven to 375 degrees F. Line a large cookie sheet with parchment paper; set aside. In a large bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add brown sugar, granulated sugar, and baking powder. Beat until combined, scraping bowl occasionally. Beat in cocoa powder. Beat in egg, maple syrup, and vanilla until combined. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour. Stir in chocolate and pecans.

Place unchilled dough in a cookie press fitted with a ribbon-shape plate. Press dough into 6-inch-long ribbons onto prepared cookie sheet. Cut each long ribbon diagonally into 2-inch lengths, forming diamond shapes. Separate shapes so they are 1 inch apart. Bake in the preheated oven for 6 to 8 minutes or until edges are firm. Transfer cookies to a wire rack; let cool. If desired, sprinkle cookies with powdered sugar and cocoa powder before serving. Makes about 72 cookies.

Layer cookies between sheets of waxed paper in an airtight container; cover. Store at room temperature for up to 5 days or freeze up to 3 months.