Line two baking sheets with parchment.
In a small bowl, whisk together the flour, cocoa, cinnamon, salt and baking soda. In a large bowl, cream the butter and sugars, about 2 minutes. Add the vanilla and eggs, one at a time, mixing well. Stir in the flour mix and fold in the chopped chocolate and nuts.
Preheat the oven to 325°F. Scoop the dough (it is quite soft) by the 1 ½ tablespoons on to the prepared pans, at least 1 ½ inches apart and chill until very cold, at least 30 minutes.
When the oven is hot, bake until just set, 12-14 minutes, rotating halfway through. When done, pull the sheets from the oven and tap gently to knock the air out of the cookies. Let cool on the sheets, set on racks. Best warm!
