Preheat oven to 350-degrees. Line a large flat cookie sheet with parchment paper and set aside. In the bowl of a stand mixer, affixed with the paddle attachment, add the butter and sugar and mix on medium-high speed until combined. Add the eggs, one at a time, into the mixture. Add the maple extract into the mixture. Scrap the sides of the bowl and then mix the ingredients on medium-high speed for 3-4 minutes or until all ingredients are thoroughly combined and mixture is creamy and smooth.

Change the mixer to low speed and slowly add the salt, nutmeg, flour and baking powder. Mix until barely combined. Add the chopped walnuts and mix until just combined. Remove the bowl from the mixer and dump the dough out onto prepared baking sheet.

Form the dough into a 4-inch wide by 18-inch long log. Sprinkle the top of the dough with sugar (if desired) and bake dough in 350-degree over for 33-35 minutes (until a light brown around the edges). Remove baked log from the oven and let set on the counter for 30-minutes before slicing the log into wedges.

After the log has cooled for 30-minutes, cut the log into 1-inch wedges. Flip the wedges so they are flat on the baking sheet and return baking sheet to 350-degree oven for 5-minutes. After 5-minutes, remove the biscotti from the oven and flip the wedges over. Return the biscotti back into the oven and bake for 4-minutes. Remove baked biscotti from the oven and let set on the cookie sheet until set. Transfer biscotti to a wire rack to finish cooling completely before storing.