Preheat the oven to 350°F and lightly grease a 9x9-inch pan. Or, use Silicone Baking Pan. In a medium mixing bowl on medium speed, mix eggs, cocoa, salt, baking powder, espresso powder, and vanilla. Mix until smooth, about 1 min.
In a medium saucepan, melt butter then add sugar. Heat slowly until sugar is dissolved. Add hot butter/sugar mixture to the egg/cocoa mixture, stirring until smooth.
Add flour and chocolate chips, stirring until smooth. Pour batter into a lightly greased 9x9-inch pan. There will likely be extra batter left over.
Bake the brownies for about 25-30 minutes. When done, toothpick or knife inserted in center will come out clean.
Remove brownies from oven and cool on a rack before removing from pan, cutting into squares, and serving.