Preheat the oven to 350 degrees Fahrenheit and line an 8"x8" glass baking dish with parchment paper.
In a large mixing bowl, whisk together the flax seeds and water. Allow to sit for a couple minutes until gel starts to form.
Add the sugar, brown sugar, oil, and almond milk. Whisk together until sugar starts to dissolve.
Place sifter over bowl and add flour, baking powder, cocoa powder, and espresso powder (if using). Remove sifter and add salt. Stir with wooden spoon just until all ingredients are incorporated.
Add chocolate chips and stir a couple times to distribute through batter.
Transfer batter to prepared baking dish. Top with additional chocolate chips. Bake for 30-35 minutes or until toothpick inserted into brownies comes out clean.
Allow to cool in the pan for 15 minutes. Lift brownies out of the pan using the parchment paper and allow to cool an additional 15-30 minutes before slicing and serving.