Sift cocoa into a separate mixing bowl. Add mochiko, salt, and espresso powder and whisk. Set aside.
Combine eggs and sugar in a mixing bowl and beat until the mixture becomes light and fluffy.
Meanwhile, melt butter (stovetop or microwave are both fine). Add chocolate chips into the warm butter and let melt, stirring gently to combine.
Add warm butter/chocolate mixture to your eggs and sugar, mixing gently.
Add dry ingredients, vanilla extract, and coconut milk, either mixing on low speed until combined or folding the batter with a spatula by hand.
Let batter sit while you grease and line an 8x8 metal baking tin. When your baking tin is ready, pour your brownie batter in; it should have thickened slightly while resting.
Bake at 350 degrees F for 25-30 minutes, or until a toothpick poked through the center comes out clean. Let brownies cool completely before slicing. Leftovers can be saved in an airtight container at room temperature.
Notes
For even wrinklier, shinier skin, try substituting a flavorless oil for the butter.