Step 1

Melt bittersweet chocolate chips and butter in a heavy saucepan over low heat, stirring constantly until melted and well-combined.

Step 2

Remove from heat, and set aside.

Step 3

In the bowl of a stand mixer fitted with a paddle attachment, beat the eggs, sugars, vanilla, baking powder, and salt on high speed 5 minutes, or until the batter is thick and creamy. This step is key, so make sure to beat the mixture for the full 5 minutes.

Step 4

Reduce the speed to low, and mix in the melted chocolate until well-combined.

Step 5

Stir in flour and cocoa powder just until combined.

Step 6

Add nuts, if using, and mini chocolate chips. Stir in to combine. The batter should be the consistency of a thick brownie batter at this point.

Step 7

Cover the batter, and chill for 30 minutes.

Step 8

Preheat oven to 350 F. Line two baking sheets with parchment paper.

Step 9

Using a 1.5 tablespoon cookie scoop, drop batter onto the prepared cookie sheets about 2 inches apart.

Step 10

Bake cookies 8-10 minutes. The cookie will look set at the edges but still be a little wet looking in the center. Don't overbake, or the cookies won't be crackly and fudgy.

Step 11

The shiny, crackly crust will develop as the cookies cool on the baking sheet.