Here we go:
In a large bowl, sift together 750 g (6 cups) all-purpose flour, 137 g (1+1/4 cups) dark cocoa powder, 1 teaspoon (8 g) salt. Set aside.
In an electric mix fitted with the paddle attachment, cream 454 g (2 cups) softened butter, 400 g (2 cups) of granulated sugar and 228 g (1 cup) of light brown sugar. Cream until fluffy and pale, about 5 minutes.
Beat in 3 cold eggs,
until just combined
Add dry mixture and mix on low speed until thoroughly combined
Add vanilla and blend.
...and wrap pressing down with the palm of your hand making a disc about 2" thick
Repeat with the 3 dough portions. Chill the 3 discs of dough for about 45 minutes.
In order to acelerate all the chill processes, you can increase the refrigerator temperature.
Meantime, you can prepare the equipment you'll need next: 7 large pieces of parchment paper - 2 for each disc of dought and one for the oven board. Your favorite cutters, rolling pin, two 1/4 wooden dowels, wire rack and a paletteknife.
Remove one disc from the refrigerator and unwrap the plastic. Place on top of a piece of parchment paper. Use a silicone rolling mat underneath to ensure it doesn't slip while rolling. Then place two 1/4" wooden dowels on either side of your dough, then another sheet of parchment paper.
Roll dough (this will require a bit of elbow grease for the first few minutes until it softens up a bit) so it's flush with dowels; they will ensure that your dough is even thickness.
You can cut a little of the tips...
...to make the dough fit between the dowels no widest than your rolling pin
Join all the trimmings and make another disc of dough. Don't need to be chilled again; only after rolling.
Preheat the oven 325ºF/160ºC.
Remove from fridge and cut your shapes using the selected cutters...
...placing them on a board lined with a silicone bakin mat or parchment paper, with 2" clearance around each one and the edge of the sheet. Chill for another 15 minutes before baking.
Bake untill cookie edges are just crisp, about 16 minutes.
Cool sheets on wire racks for about 5 minutes, then gently remove cookies and place on wire racks to finish cooling.
It yelds about 40 medium cookies, depending on shape/size.
Ok, you can't do this cookies if you're in a hurry, but if you find motivation to do something special, it really, really worth it.
Enjoy!!