Whisk together the dry ingredients in a large 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 light-colored and fluffy. Then add in your eggs, one at a time, beating them in completely after each addition. Add in the vanilla.
Slowly add in the dry mixture little by little, beating into the wet mixture until it has all been added and mixed in thoroughly.
Using the mixer on the lowest speed setting, add in the whole bag of chocolate chips and mix until they are just evenly through the dough.
Take a large tablespoon of the batter and flatten it slightly on your palm. Take a peppermint patty and place on the dough. Top with another 1/2 tablespoon of dough and round out nicely into a dome shaped cookie (see pictures)
Bake in the preheated oven for 15-17 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. These will take longer than normal cookies due to their size. After a minute of so of cooling on the sheets, remove the cookies onto a rack to cool.