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 mix well.
Add baking powder and flour and mix until a stiff dough forms and starts to pull away from the sides of the bowl as you mix.
Take half the chocolate chunks, and chop them into little 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 dough in the fridge for 2 hours, or in the freezer for 20 minutes.
Preheat oven to 350.
Slice cookies about 1/2" thick. Place on ungreased baking sheet. Sprinkle lightly with sea salt.
Bake on the middle rack for about 10 - 12 minutes, or until the edges are golden brown.