In a large bowl, whisk together the butter and light brown sugar until well combined. 

Next, add the egg and vanilla. Whisk to combine. 

Add the flour and baking soda and mix just until no large lumps of flour remain. 

Finally, add the butterscotch chips and fold them into the cookie dough.

Cover the cookie dough and place it in the fridge to chill for 30 minutes. While the dough chills, preheat the oven to 375F.

When the dough has chilled, prepare two large baking sheets with parchment paper. 

Scoop out 2-tablespoon sized portions onto the baking sheet and press them down to form a ½” thick disc. 

Bake for 12-14 minutes, or until the edges of the cookies are golden brown and the centers are just set. 

Sprinkle over flakey sea salt, if using and allow the cookies to cool completely on the pan.