Mexican Walnut Cookies (Polvorones)

I was watching Food Network the other day and I saw Marcela Valladolid make these cookies.  I love walnuts so I knew I had to give them a try.  I sure am glad I did because they are amazing!  There is so much flavor in them.  They're also a breeze to make.  Enjoy!
-1 cup (2 sticks) unsalted butter, at room temperature
-1/2 cup granulated sugar
-2 cups flour
-1 cup chopped walnuts
-1/2 cup ground walnuts
-powdered sugar
Beat sugar until light and fluffy.  Add granulated sugar and beat until well blended.  Add flour and all walnuts.  Remove the dough from the bowl and form into a large disc.  Wrap the dough in plastic and chill in the fridge for 30 minutes.
Preheat the oven to 325 F.  Line two baking sheets with parchment paper.
Remove dough from fridge.  Cut it into quarters, then cut each quarter into sixth for a total of 24 equal pieces.  Roll each piece of dough between your palms into 2 inch balls.  Arrange the balls onto the prepared cookie sheets.  Bake in preheated oven for 20-25 minutes.
Cool the cookies on the sheet for 5 minutes, then toss them in the powdered cookies.  Cool completely and enjoy!