Make a chocolate Cake
Yes, that amount of cocoa will change the batter. It will make the cake drier. 

The more cocoa powder you add the more sugar and moisture you will need to prevent the cake from getting dry.

I would take out a 1/4 cup of the almond flour and add a 1/4 cup of cocoa powder. If you feel you would like a little more go buy a tablespoon at a time after that.