Cream together the butter and sugar in a medium bowl. Then add the vanilla and one egg at a time. Beat on low with a mixer.
In another bowl, sift together the flour, Hershey's cocoa, baking soda, and salt. Add the flour mixture into the butter mixture slowly, and beat it until it's well-blended. Add the chocolate chips and mix again.
Spoon the cookie batter about 2 inches apart onto a cookie sheet. Bake for about 10-12 minutes. Allow them to cool for a couple of minutes and then serve warm.
Notes
Be sure to not overcook the cookies because they'll be too crunchy.
Make sure the butter is room temperature softened, not heated in the microwave so that the cookies don't spread out too thin while baking.