Put chocolate in a microwave safe bowl and pulse for 10 seconds at a time until melted. Set aside.
Whisk together flour, cocoa powder, espresso powder, baking powder, and salt until well combined.
While the chocolate is still a little warm, use an electric hand-mixer or stand-mixer to combine the sugars and melted chocolate. Beat at medium-high speed until the sugar dissolves.
Next, beat in the eggs and vanilla until well-combined.
Stir in the oil.
Add in the dry ingredients. Start mixing on a low speed to avoid a flour cloud. Then increase to medium-high speed until well-comined.
Cover bowl and put in refridgerator to chill dough for 20 minutes.
Preheat oven to 350° F
Once the dough has chilled, measure out 30 g (1½-2 tbsp) of the dough and shape into balls.
Place 3 inches apart on a parchment lined baking sheet.
Bake on middle rack until edges seem set - about 10 minutes.
Cool on tray for 5 minutes. Then transfer to wire rack to cool completely.