Preheat oven to 350°F (175°C) and line your pan with parchment.
Mix ground flaxseed with water. Let it sit for 5 minutes.
In a large bowl, whisk together espresso, melted coconut oil, vanilla, and flax mixture.
In another bowl, combine flour, cocoa powder, baking soda, sugar, and salt.
Add wet mixture to dry and stir until a thick batter forms.
Fold in chocolate chunks. Try not to eat half the batter.
Pour into the prepared pan and spread evenly.
Bake for 30 minutes or until a toothpick comes out with fudgy crumbs.
Cool for 10–15 minutes before cutting, unless you like molten brownie chaos.
Serve warm, chilled, or directly from the pan with zero regrets.