Instructions
Preheat the oven to 350 degrees (F). Line an 8×8 inch mold with parchment paper. Spray parchment, and any exposed pans, lightly with a non-stick spray, set aside.
In a saucepan over medium heat, melt the butter until golden brown (see post for more information on this if needed).
Remove from heat and cool for a few minutes, then scrape the butter into a large heatproof mixing bowl.
Beat in brown sugar and mix until well blended. Add bourbon and vanilla. Then add the egg and egg yolk, beating until combined.
With a rubber spatula, add the flour, the cinnamon and the salt, mixing until they are well combined. Finally, add the nuts and the chocolate. Scrape the dough in the prepared pan.
Bake for 24 minutes, or until the edges are firm and golden and the center wobbles a little.
Let cool in the pan for at least 1 hour before cutting. Sprinkle with flaky sea salt before serving, if desired.