Preheat oven to 350°F (175°C).

Line an 8x8 inch pan with parchment paper and lightly grease it. Set aside.

In a small bowl, stir together the ground flaxseed and hot water.

Let the flaxseed mixture sit for 15 minutes until it thickens and becomes stretchy.

In a large bowl, combine white sugar, brown sugar, and melted vegan butter.

Add the flaxseed mixture and vanilla extract to the wet ingredients, stirring well.

In a medium bowl, sift together all-purpose flour, cocoa powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the vegan chocolate chips.

Pour the batter into the prepared pan and bake for 25-30 minutes, or until a toothpick inserted into the center comes out with moist crumbs.