Make the flax “eggs” by stirring together the ground flax seed and water in a small bowl until well combined. Allow mixture to sit 10 to 15 minutes, stirring occasionally, until substance resembles beaten eggs.

Preheat the oven to 350 degrees F.

Add all ingredients for the brownies to a stand mixer (including the flax eggs) and beat until combined. The brownie “batter” will be very thick and appear crumbly. This is normal!

Transfer brownie batter to the parchment-lined loaf pan and smooth into an even layer. Don’t worry if the batter looks grainy or oily.

Bake on the center rack of the oven 20 to 25 minutes, until the edges are set up.

Remove brownies from the oven and allow them to cool at least 30 minutes.

Stir together the peanut butter topping in a small bowl until well-combined. Once brownies are cool, spread the peanut butter topping over the brownies and top with chocolate chips (and a sprinkle of sea salt if desired)!