Line cookie sheets with silicone liners or parchment paper. Preheat your oven to 375°.
In a large bowl, combine the butter, sugars, and cocoa powder. Beat with an electric mixer for 2-3 minutes. Beat in the eggs and vanilla.
Add the flour, baking soda, and salt. Stir into the creamed mixture with chocolate chips. (I like to set aside some of the chocolate chips to press on top of the cookies.)
Scoop dough by tablespoonfuls and roll into balls. Place about 2 inches apart on prepared baking sheet.
Bake at 375° for about 8 minutes, or until the center is barely set. Immediately press a few chips into the top of each cookie.
Transfer to a cooling rack to cool completely.
Notes
For pretty, bakery style cookies, either reserve some chocolate chips, (or use extra chocolate chips) and press a few on top of each cookie as soon as it comes out of the oven.
Don't overbake the cookies, or they won't be soft and fudgy. They may not appear quite done, but they will continue to cook after you remove them from the oven.
I used a 1 1/2 tablespoon scoop, which is about an ounce. If your cookie dough balls or larger or smaller, you will need to adjust the baking time.
Cookies can be stored in an airtight container for up to a week, or you can freeze them for 5-6 months.