Preheat oven and line 12 cup muffin pan

In a large bowl, whisk together flour, cocoa powder, espresso, baking powder, sea salt and chocolate chunks and set aside

In a medium bowl, lightly beat the eggs then add in the remaining ingredients and stir well

Pour the egg mixture into the flour mixture and stir until just combined

Spoon into prepared liners and bake for 20-22 minutes, testing with a toothpick

Let cool for 10-15 minutes