- In a medium size mixing bowl or your favourite stand mixer with the paddle attachment, cream together the softened butter and sugars.
- Stir in the vanilla paste and egg until combined.
- In another mixing bowl, whisk together the flour, cocoa, espresso powder, baking powder, baking soda, and salt.
- Mix the dry ingredients in with the wet ingredients and stir until a thick batter forms.
- Stir in the chopped dark chocolate.
- Wrap up in plastic and let it rest in the freezer for 10 min
- Wrap up in plastic and let it rest in the freezer for 10 min
- Spoon or divide equally and roll between your hands onto a baking sheet lined with a baking mat or parchment paper. Top with flaky sea salt if using.
- Bake at 325°F for 11 minutes. Allow to cool on baking pan before moving to a cooling rack.