In a small skillet over medium heat, melt the butter until it begins to foam. Continue to cook and stir frequently until it turns amber in color. Remove from heat and pour into a small bowl. Scrape the brown bits into the bowl with the melted butter as well. Allow the mixture to solidify but remain as soft as you would use for typical cookies. To speed up the process, you can place in the refrigerator. If you'd like, you can also do this a few days in advance and store in the refrigerator. Just pull from the refrigerator 30 minutes before using to allow to soften.
Stir together flour, cinnamon, salt and baking soda in a small bowl. Set aside.
Cream together the solid brown butter with dark brown sugar and white sugar in a stand mixer or mixing bowl with hand mixer until light and fluffy. If using a KitchenAid stand mixer, I find four minutes on speed four is perfect.
Scrape the creamed butter off the side of the bowl. Add one egg, bourbon if using and vanilla extract and beat until combined. Repeat with the second egg. Once both eggs are combined, scrape the dough off the side of the bowl again.
Add a spoonful or two of the flour mixture at a time and stir until incorporated. Repeat until all the flour mixture is combined into the dough. Stir in chocolate chips.
Chill the cookie dough in the refrigerator for at least an hour. You'll notice this dough is softer than your typical chocolate chip cookie dough, so giving it enough time to chill is important to prevent overspreading. You can chill for longer if you'd like --- even up to overnight.
Heat oven to 375 degrees. On a parchment paper-lined baking sheet, form the dough into golf ball-size dough balls. This may be bigger than some cookie recipes, but the large dough balls will keep the cookies extra soft. If you'd like, top with additional chocolate chips.
Bake for nine minutes. Allow to cool on the pan for a couple minutes and then move to a wire rack to cool completely. Store in an airtight container. Enjoy!