Starting with cold butter, smash and whip it until it gets a bit softer and lighter (but not melted).
Add the sugars and the orange zest. Beat well until light and fluffy.
Add in the egg and vanilla and mix well.
Add baking powder and flour and mix until a stiff dough forms. It should start to pull away from the sides of the bowl as you mix.
Chop half the chocolate chunks into small pieces, some as small as shavings. Add all of the chocolate, of varying sizes, to the bowl and mix it in.
Roll the dough in a large sheet of parchment paper into a long log, about 1 1/2" thick. Chill in the fridge for 2 hours or in the freezer for 20 min. (if you're impatient like I was).
Preheat oven to 350ºF.
Slice cookies about 1/2" thick. Place on an ungreased baking sheet. Sprinkle lightly with sea salt.
Bake on the middle rack for 10 - 12 minutes or until the edges are golden brown.