Add to the butter the sugar, baking powder and cocoa powder and beat until well combined.
Beat in the two eggs. Then add in one cup of flour and beat. Add in the rest of the flour and stir to combine.
Stir in the vanilla and chocolate chips.
Roll the dough into two logs about 8-9 inches long. Place on a lined or greased baking sheet.
Flatten the dough slightly. Then bake 375 degrees for 20-25 minutes. Test for doneness by inserting a toothpick in the center, if it comes out clean they are done baking.
Cool on the cookie sheet for 45 minutes to 1 hour.
Cut each roll on the diagonal, into 1/2 inch slices. Place cut side down on cookie sheet.
Reduce oven temperature to 325 degrees and bake 7 minutes. Turn each cookie over and bake another 7 minutes.
Cool on a wire rack.
Notes
There is one hour of cooling time included in the total time for these cookies.