In a medium bowl, vigorously whisk together the all-purpose flour, baking powder, and kosher salt to ensure the leavening agents are perfectly distributed.

In the bowl of an electric stand mixer, cream the softened butter, granulated sugar, and dark brown sugar on medium-high speed until the mixture becomes highly pale, aerated, and fluffy.

Reduce the mixer speed and carefully blend in the natural cocoa powder and the black cocoa powder until the emulsion turns a deep, rich brown.

Stream the eggs and pure vanilla extract into the cocoa-butter emulsion, mixing until completely unified and smooth.

Gradually fold the dry flour mixture into the wet ingredients in three additions. Mix only until the flour is just combined (no white streaks should remain) to prevent overworking the gluten, which leads to tough cookies.

Gently fold in the mini semi-sweet chocolate chips until evenly dispersed throughout the dark dough.

Divide the unified dough tightly into two equal halves. Form and roll each piece into a uniform, tight cylinder (log) and wrap securely in heavy plastic wrap.

Refrigerate the wrapped dough logs for a minimum of 1 hour. This critical thermal resting phase solidifies the butter, deeply hydrates the flour, and ensures the cookies maintain their perfectly round, sharp edges when sliced.

Preheat the oven to 350°F. Line heavy metal baking sheets with parchment paper or silicone baking mats.

Remove one chilled dough log from the refrigerator. Using a sharp chef's knife, slice the log into uniform ¼-inch thick rounds.

Place the precise rounds onto the prepared baking sheets, leaving 1 inch of space between each.

Heavily sprinkle the top of each unbaked cookie round with the wild blueberry sugar, pressing it gently into the surface so it adheres.

Bake in the preheated oven for 10 to 12 minutes, until the cookies are just firm to the touch.

Allow the cookies to cool on the baking sheet for 2 minutes before transferring them to a wire rack to cool completely, allowing the intensely dark crumb to set.