3/4teaspoonsalt (kosher or finely ground sea salt will work)
2sticks unsalted butter, at room temperature
1cuplight brown sugar, packed
2large eggs, at room temperature
Line a large baking sheet with parchment paper; set aside.
Preheat oven to 375 degrees (F). In a medium sized bowl add the flour, cornstarch, cocoa powder, salt, and baking soda; whisk well to combine and set aside. In a large bowl using a handheld electric beater, or in the bowl of a stand mixer fitted with the paddle attachment, beat the butter and vanilla together on medium-speed until smooth and creamy. Add in both sugars and beat until light and fluffy; about 2 minutes. Add in eggs, one at a time, beating well after each addition. Gradually add in the dry ingredients, mixing until just combined. Using a rubber spatula, fold in chocolate chips and butterscotch chips. Drop 2 tablespoon sized balls of dough onto the prepared sheet, leaving 1" between each cookies for spreading. Bake for 9- 12 minutes (depending on your oven), or until the edges are set and centers look just slightly underdone. Cool for 5 minutes on the cookie sheet before transferring to a wire rack to cool completely.