In a large bowl whisk together the flours and sugar then make a well in the middle and add the egg yolk, butter and vanilla, mix with a fork until almost combined. This dough is also very easy to make with a Food Processor.
Move to a lightly floured flat surface and knead into a compact ball, wrap in plastic and refrigerate for one hour.
Pre-heat oven to 350 F (180C) and line cookie sheets with parchment paper.
Remove the dough from the fridge and on a lightly floured flat surface roll into a 1/4 inch (1/2 cm) thick rectangle, with your favourite cookie cutter cut out cookies (I used mini cutters and got a lot of cookies, the first photo I used a medium round cutter and I got 15 cookies).
Place cookies on prepared cookie sheet and bake for approximately 6 minutes (for mini cookies) approximately 8 - 10 minutes for larger. Do not let the cookies brown. Let cool on cookie sheet, then dust with powdered / icing sugar. Enjoy!
If dough is too crumbly add a little extra tablespoon of softened butter.