Preheat the oven to 180°C (350°F). Lightly grease a 23x23cm/9x9 in a square pan with a little bit of vegan butter. Then line the pan with a strip of parchment paper.
Combine psyllium husk with 2 tbsp of water. Mix well and set aside.
In a small saucepan, melt vegan butter over medium heat. Then add brown sugar and white sugar. Whisk until the sugar slightly melt. Then take it off the heat.
Pour the sugar-butter mixture into a mixing bowl and whisk in psyllium 'egg'. After it's combined, slowly whisk in aquafaba. Then, use a spatula to mix in melted chocolate. Make sure it's all well combined.
To the wet mixture, sift the cocoa powder, all-purpose flour, ground coffee, baking powder, and sea salt. Mix until combined. Don't overmix the batter. Mix in chocolate chips or chunks (or you can sprinkle them on top of the brownies in the pan).
Pour the batter into the prepared baking pan and spread it evenly. Bake it in preheated oven for 20 minutes. Brownies are done when a toothpick inserted in the middle comes out with a few moist crumbs. If it looks too wet, bake for additional 5 minutes because all ovens vary.
Remove the brownies from the oven and place them on a cooling rack. Let them cool completely in the baking pan before cutting into squares.
Enjoy!