In a microwave-safe bowl, melt 1 cup dark chocolate chips on medium power in 30-second intervals until just melted.
Sift the flour, Cocoa Powder, salt, baking soda, and baking powder together into a large mixing bowl.
In a large mixing bowl beat the butter, brown sugar and granulated sugar until fluffy.
Mix in the eggs one at a time, then add the vanilla. Add melted chocolate and mix until combined.
Mix in the flour mixture by hand until combined (this avoids a cake like consistency).
Fold in the chocolate chips.
Spread the dough into the prepared pan and smooth the top. Bake for 30 minutes. After 30 minutes, give the pan a little shake. If it jiggles in the middle, put the pan back in and try again every 5 minutes until there is no longer any jiggle.