Add the butter to a medium sized skillet and cook over medium heat. Stir continuously, butter will start to boil and foam. Stir for another minute or so until butter starts to brown, pour into a tin container (I used a bread pan). You'll be able to see what looks like amber sand in the bottom of the pan. The whole browning/cooking process took about 10 minutes. Allow butter to cool in fridge for 1 to 2 hours. Then remove from fridge and allow it to soften to room temperature.
Mix together the flour, baking soda, baking powder, and salt in a large bowl and set aside.
In a stand mixer fitted with a paddle attachment, beat together browned butter and sugars. Mixture will be a bit crumbly.
Add in eggs one at a time and mix until combined after each addition.
Add vanilla extract and bourbon and mix until smooth, mixture should resemble frosting.
Slowly add in flour mixture a half cup at a time and beat until just mixed in.
Fold in the chocolate chips and toffee bits.
Wrap dough up in plastic wrap and chill for at least 2 hours, preferably overnight. This is absolutely necessary so your cookies aren't hard.
When you're ready to bake cookies, preheat oven to 350 F.
Place rounded tablespoons of cookie dough on a parchment lined baking sheet at least 2 inches apart.
Bake for 11-13 minutes until edges are golden brown. 12 was my magic number!
Let cookies cool on baking sheet for two minutes before transferring to a cooking rack to cool completely.