To make the cookies, place chocolate, oil, sugar, vanilla and milk in a heat-safe bowl on top of pot of simmering water, stirring until the chocolate is melted and then whisk in your eggs until the whole mixture is smooth and shiny.
In another bowl whisk together the all-purpose flour, bread flour, cocoa powder, sea salt, baking powder and baking soda. Pour the flour mixture into the chocolate mixture and give a couple of stirs until the dough is just starting to come together. Fold in the chocolate and hazelnuts. Either wrap tightly and chill the cookie dough for 20 to 30 minutes in the fridge or let sit on the counter until the dough has firmed up a bit.
Preheat your oven to 350 F and line your baking sheets with parchment paper.
Gently roll 2 tablespoons of dough into a ball and place on the cookie sheet allowing about 2 inches between each dough ball. Bake one sheet at a time in the center of the oven for 9 minutes. You want to slightly under bake these. Allow the cookies to cool on the sheet for 15 minutes then transfer to a cooling rack.