Preheat your oven to 350°F (175°C) and line a large cookie sheet with parchment paper.

Cream the softened unsalted butter, granulated white sugar, and brown sugar until smooth and fluffy, about 2 to 3 minutes.

Incorporate the egg and pure vanilla extract, mixing until just combined, about 30 seconds.

Sift the unbleached flour, unsweetened baking cocoa, baking soda, and salt into the mixing bowl and fold until just incorporated.

Fold in the chocolate chunks and mini semi-sweet chocolate chips.

Scoop rounds of dough onto the prepared cookie sheet, spacing them about 2 inches apart.

Bake for 9-10 minutes, allowing the edges to set while keeping the centers gooey.

Press additional chocolate chunks and chips into the tops of the cookies immediately after baking.

Cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.