Preheat oven to 325 degrees F. Line a 9-inch square baking dish with parchment paper, making sure there is some overhang on either side. Grease with cooking spray, set aside.

In the bowl of a food processor, combine 3/4 cup toasted hazelnuts, coca powder, salt, cinnamon and 1/2 cup sugar. Pulse until finely ground, and resembles ground coffee.

Melt the butter in a medium saucepan over moderate heat and cook until the foam subsides and the butter is nutty and golden and brown bits form at the bottom. Remove from the heat and immediately add the chopped bittersweet chocolate. Let sit for about 5 minutes and then stir until fully melted and glossy. Let cool slightly.

In the bowl of a stand mixer, fitted with the paddle attachment, beat the eggs together with the remaining 1 cup sugar and espresso/water mixture on high until thick and tripled in volume, about 5 minutes. Stir in the chocolate butter mixture and mix until well combined. Add the finely ground hazelnut cocoa mixture and stir until fully incorporated. Stir in the remaining hazelnuts (roughly chopped) and chocolate chips and fold to combine. Pour the batter into the prepared pan and spread out evenly with a rubber spatula. Bake until the top is glossy, and a toothpick inserted in the middle comes out clean, about 45 to 50 minutes. Remove from oven and let cool on a wire rack. Place them in the fridge to chill and then slice and serve with a scoop of ice cream. Wrap each brownie individually with plastic wrap and keep at room temperature for up to 2 days.