Whisk together the dry ingredients in a medium bowl, making sure that the cocoa isn't lumpy and is well mixed in.
In your mixing bowl, cream together the butter and sugars until it's light-colored and fluffy.
Then add in your eggs, one at time, beating them in completely after each addition. Stir in the vanilla.
Using the mixer on the lowest speed setting, slowly add in the dry mixture little by little, until it has all been added and mixed in thoroughly. Add in the whole bag of chocolate chips and mix until they are just evenly through the dough.
Drop by rounded tablespoonful onto ungreased or parchment-lined cookie sheets. Bake in the 350 °F oven for 9-10 minutes.
Remember that the key to wonderful cookies is just under baking them by a minute or so and this is especially important with these cookies as the cocoa can dry things out. After a minute of so of cooling on the sheets, remove the cookies onto a rack to cool completely.