Preheat the oven to 350F.
On a baking sheet, toast walnuts for 5 to 6 minutes. Alternatively, toast in a non-stick skillet over medium-high heat stirring constantly. Set aside to cool. Once cooled, roughly chop until they're the size of chocolate chips.
Sift the flour, baking powder, cocoa powder, cinnamon, and ginger. Then stir in the sugars and chopped walnuts.
Add the eggs to the dry ingredients one at a time. Then add the softened butter and Vin Santo. Mix well until smooth and doughy.
Line baking sheets with parchment paper. To form the cookies, lightly flour your fingers. Scoop out a ball of dough the size of a golf ball. Using as little flour as possible, flatten the ball into an oblong shape with slightly pointed edges. Use only enough flour to work the dough and keep the cookies from sticking to the parchment paper. Make sure to leave some space between each cookie.
Bake for 5-10 minutes, until slightly puffed with slight cracking on top. Remove from the baking sheet and allow to cool on a rack. When cool, dust with powdered sugar and serve.