In a large bowl, combine butter at room temperature and both sugars until creamy. Add the eggs and vanilla extract and mix until smooth.
1 1/2 cups white sugar, 1/2 cup packed brown sugar, 1 cup unsalted butter, 2 large eggs, 2 1/2 tsp organic vanilla extract
In another bowl, combine sifted flour, baking soda, baking powder, sifted cocoa and salt.
2 cups all-purpose flour, 3/4 cup extra dark cocoa powder, 1 1/2 tsp baking soda, 1 1/2 tsp baking powder, 1 tsp salt
Cup by cup, pour the flour mixture into the butter mixture and mix until well combined.
Add the chocolate chunks, fold in with a spatula, and refrigerate the dough for 2 hours.
1 cup milk chocolate chunks, 1 cup dark chocolate chunks
Preheat oven on 350°F/170 C and line baking sheet with parchment paper.
Scoop the cookie dough one by one, with a help of ice cream scooper, onto the baking sheet (for larger cookies, measure 2 scoops).
Bake for 8-10 minutes or until the edges are slightly crisp, yet soft in the middle. If they are no more sticky (except the chocolate part), it means they are done. If you like them more gooye, leave them in the oven 2 minutes less.
Take the baking sheet out from the oven and let stand on the cookie tray for 5 minutes to cool down.