1cup2 sticks unsalted butter, melted and slightly cooled
3/4cupsugar
1teaspoonvanilla extract
1cupsemisweet chocolate chipsmelted and slightly cooled
1egg
1 1/2cupsunbleached all-purpose flour
3/4cupDutch-processed cocoa powder
1teaspoonkosher salt
1/2teaspoonbaking soda
For the filling:
1/2cup1 stick unsalted butter, softened
1 2/3cupsconfectioners’powdered sugar
1teaspoonvanilla extract
1Tablespoonmilk
Pinchof kosher salt
Food coloroptional
Instructions
In a stand mixer with whisk attachment, whisk the butter and sugar until well combined. Add in the vanilla and chocolate, then whisk in the egg until combined.
In a separate bowl, whisk flour, cocoa, salt, and soda until combined. Stir the flour mixture into the chocolate mixture. Let the dough sit for an hour to firm up.
After an hour, turn the dough out onto waxed paper. Use a spatula to shape the dough into a log about 2 1/2 inches in diameter along the edge of wax paper. Start rolling the dough and shaping as you wrap and roll. Try to keep the paper tight and push the ends of the log so that they are flat. Twist the ends of the waxed paper to secure. Refrigerate for at least two hours or until firm. If log settles and flattens on one side, rotate every 15 minutes or so to maintain a round shape.
Heat oven to 325 degrees and line baking sheet with parchment paper.
Slice dough into quarter-inch-thick slices and place on prepared baking sheet. Bake for about 20 minutes or until cookies are firm to the touch. Note: Bakerella under-baked her cookies by half the time and said they were fine, so I followed her suggestion. I was worried about charring them since they're black already and there's no golden brown edge to go by! Mine were fully cooked and soft, I imagine if you cooked them the full time you would end up with a hard cookie much more like an Oreo. It's all up to you and what you prefer.
Let cookies cool on a rack and prepare the filling. In a stand mixer with paddle attachment, beat the butter until smooth and creamy. Add sugar and vanilla and beat until smooth. Add the milk and salt and continue beating until smooth again. Place about a tablespoon of filling on the bottom of one cookie and sandwich with a second. Repeat with remaining cookies and enjoy!