In a small saucepan over medium heat, melt the butter. Once melted, stir constantly with a wooden spoon until most of the foam subsides and the butter has turned a medium brown color and smells toasty like caramel (about 7 minutes). Pour into a heat safe bowl and let cool most of the way.
Preheat oven to 350℉. In a large bowl, mix together the butter, vanilla, espresso powder and sugars until well combined. Mix in the egg until combined. Add the flour, baking powder, baking soda, salt and cinnamon and mix again until no dry flour remains. Fold in the butterscotch chips and chopped chocolate.
Scoop out about 2 tablespoons of cookie dough and roll into a ball (you should get about 12 cookie dough balls). Place on a parchment lined baking sheet about 2 inches apart. Top with a few more chips and chopped chocolate. Bake for about 10 minutes-11 minutes or until edges are mostly set and the centers are under done.
Remove from oven and sprinkle flaky sea salt on each cookie. Let the cookies set for about 5 minutes before transferring to a cooling rack. Serve warm. Store in an air-tight container for up to 5 days.