Preheat your oven to 425°F (220°C) and line a muffin tin with parchment liners.

In a medium bowl, whisk together flour, cocoa powder, baking soda, baking powder, and salt.

In a separate large bowl, combine espresso, sugar, eggs, and buttermilk. Whisk until smooth.

Slowly drizzle in melted butter while whisking until fully incorporated.

Gently fold the dry ingredients into the wet mixture using a spatula until just combined.

Stir in chocolate chips, reserving a few for topping.

Fill each muffin cup to the top with the batter.

Bake in the preheated oven at 425°F (220°C) for 5 minutes, then reduce to 350°F (180°C) and bake for another 10-12 minutes.

Allow to cool in the tin for 5-10 minutes before transferring to a wire rack.