Decadent Double Chocolate Chip Cookies

1⅔ c flour (205 g) combine beat stir bake 9–11 minutes at 375°F cool first on sheets, then on racks
⅓ c cocoa (40 g)
1 t baking soda
½ t salt
1 c butter (227 g) cream
¾ c lightly packed brown sugar (150 g)
½ c granulated sugar (94 g)
1 egg
1 t vanilla
297 g dark chocolate chips  
1¼ c (~130 g) coarsely chopped pecans (optional)