Preheat oven to 350 degrees F. Grease an 8 inch pan with coconut oil (or any other vegan fat you like) and line with parchment paper. If desired, grease the parchment with a little more coconut oil and sprinkle some sea salt across the bottom. This gives an extra bite of salt in each bite of brownie.
In a mixing bowl, mix the boiling water, unsweetened chocolate and cocoa powder and stir until smooth. Let cool slightly.
Add both sugars, oil and vanilla and stir until smooth.
Mix together the flour, baking powder and salt, then stir into the batter. Make sure the batter is not so hot that it will melt the chips, then stir in the chocolate chips. Give the batter 40 or so good strokes with a heavy duty scraper.
Spread mixture in the pan. If desired, spread nuts over the top. and bake on center rack for 25-30 minutes or until brownies appear set (the middle should puff up slightly and will lose its glossiness). Let cool completely and chill. Lift from pan and cut into squares.