1. In a large bowl, combine cocoa powder, sugars, salt, flour and chocolate chips.
2. Store in an airtight container until ready to use.
3. When ready to make, preheat oven to 350. Line a 9x9 square pain with foil or parchment paper, leaving about a 2 inch overhang on two sides. This will allow you to lift the whole tray of brownies straight out of the pan.
4. Empty dry brownie mix into a large bowl and add eggs, vegetable oil, water and vanilla extract. Stir with a rubber spatula to combine (mixture will be very thick).
5. Pour brownie batter into prepared dish; smooth top. Bake 25-35 minutes until a toothpick inserted into the center comes out clean.
6. Remove from oven and place on a cooling rack. Let cool about 15 minutes and then gently lift brownies out of pan back onto the cooling rack.
7. Cool completely before cutting into squares.