Double chocolate cookie bars

1 ½ cups cake flour
1 ½ cups bread flour
½ cup cocoa powder
1 ¼  ts baking soda
1 ½  ts baking powder
1 ½  ts coarse salt
2 1/2 sticks (1 1/4 cups) unsalted butter
½ cup light brown sugar
½ dark brown sugar
1 cup granulated sugar
2 large eggs
1 ½ cups bittersweet chocolate chips (use one with a high cacao like Ghiradelli)
couple handfuls of chopped pecans (or walnuts), optional

Cook Notes:  

I do not recommend using milk chocolate chips in this recipe—it would be overkill sweetness. 
I divided the dough into 2/3 and 1/3 piles, as I wanted the top of the cookie bars to have a nice crunch to them.  
The 2/3 is the bottom/pressed in layer, and then the 1/3 is left like a crumble topping—loosely placed on top, as I did with the sprinkling of the nuts.
It truly needs a couple hours to firm up/set up.  If you dig into this straight out of the oven it will be very gooey and delicate—which isn’t a bad thing.  
But it’s also very good in a harder, cookie-like version. 
Lastly, you all know by now I don't have a mixer so I did this recipe by hand. 
The dough is very tough and hard to mix, so I used my hands--great workout! But if you have a mixer, please go ahead and use it.

Sift flours, baking soda, baking powder, cocoa powder, and salt into a bowl. Set aside.
Using a mixer fitted with paddle attachment, cream butter and sugars together until very light, about 5 minutes. 
Add eggs, one at a time, mixing well after each addition. 

Reduce speed to low, add dry ingredients and mix until just combined, 5 to 10 seconds. 
Drop chocolate pieces in and incorporate them without breaking them. 
Press plastic wrap against dough and refrigerate for at least 4 hours, preferably overnight.
When ready to bake, preheat oven to 350 degrees. 
Spray a 9 x 13 pan with non-stick spray.
Divide dough into 2 piles: 2/3 and 1/3.
Take the 2/3 dough and line the bottom of the baking pan with it, making sure to get all the corners, 
making sure there aren’t any holes or gaps in the dough.
Take the 1/3 remaining dough and in clumps, place on the top. Also make sure to take any dough and close up any gaps you see in the corners.
Don’t push the crumble down into the dough, just leave it on the top—it’s ok to have spaces in the crumble—
gaps are good on the top, it will let crumbles will bake up nice & crisp. If you want to add nuts then sprinkle on a couple handfuls of chopped nuts. 
Bake until golden brown but still soft, roughly 25 – 34 minutes. 
Look for golden brown edges, non-jiggly middle.
The middle will be a bit soft, but once it completely cools it won’t be as gooey; it sets up really nice.
You really have to let this cool at least an hour before slicing.
Slice with a sharp knife.
Makes about 20-24 bars depending on how you cut them.