Make the flax eggs by stirring the ground flax and water in a small bowl. Set aside to thicken. 

Preheat the oven to 350 degrees F and line a 7 x 11 pan with parchment paper.

Melt the vegan butter.

In a large bowl, whisk the melted vegan butter and sugars together. Add the flax eggs and vanilla, and whisk until evenly combined.

Over the same large bowl, sift in the flour and cocoa powder. Add the salt and baking powder and stir with a large wooden spoon until just combined. Do not over mix. 

Fold in half of the chocolate chips. Pour the batter into the prepared pan and smooth out the top with a spoon or your hands. Sprinkle the rest of the chocolate chips on top of the batter.

Bake for 35-40 minutes. The brownies may still be bubbling and not look done, but they will firm up a lot as they cool.

Remove from the oven, allow to cool in the pan for 15 minutes, then pull the brownies out, using the parchment paper and let cool for another 15-30 minutes before slicing and serving.