Preheat the oven to 350F. Grease and line a 9in x 9in pan with parchment paper (you could use an 8in x 8in pan as well, but the brownies will be thicker).

Pulse the almonds in a food processor for 5-10 seconds intervals. About 10 pulses should get the almonds finely ground. Transfer to a large mixing bowl.

Sift the flour, arrowroot, cocoa, salt and baking soda into the same mixing bowl as the almonds. Whisk well to combine, set aside.

In a small bowl combine the flax and water, set aside.

Place the vegan butter in a microwave safe container and microwave at half power for 30 seconds (you can also melt the butter on the stove if you don't have a microwave). Add the 3/4 cup chocolate chips and continue to microwave at half power for 30 second intervals, stirring in between each, until the chocolate is completely melted.

Stir the sugar into the melted chocolate mixture, followed by the rice milk, vanilla and flax. Whisk well to combine.

Pour the chocolate mixture into the bowl with the dry ingredients and mix well to combine. The batter will be very thick.

Fold in the optional chocolate chips and then spoon into the prepared pan. Use a spatula to spread evenly, you can also wet your hands and press the batter into the pan to smooth it out.

Bake at 350 for about 35 minutes or until a toothpick comes out somewhat clean.

Let cool for at least 2 hours before cutting.