Preheat oven to 365 F. Combine dry ingredients in a bowl. Set aside.
Beat the butter and sugars together in another bowl. To avoid incorporating air into the dough which increases cookie spread, beat the butter and sugars just until the mixture is thoroughly combined.
Mix in the eggs and vanilla. Add in half the flour-cocoa mixture and mix just until the flour settles and then add in the remaining flour mixture, beating no longer than it takes to fully incorporate the ingredients.
On a lightly floured surface roll the dough to your desired thickness and then cut your cookie shapes, place them on a parchment lined baking sheet, and slip the sheet onto the middle rack of heated oven. The baking time will vary between 8-15 minutes depending on the thickness and size of the cookies.
Using brown sugar creates a more dense cookie with a deeper flavor. I tend to use brown sugar with more adult flavorings like nuts, brown butter, or liquor. Try replacing that second 3/4 cup of sugar with powdered, light brown, dark brown, turbinado, muscavado or any variation of sugar that rings your bell. Or just use all white granulated. Every variety will make small changes to the taste and mouth feel (texture) of the cookie.
I prefer using a half and half mix of Hershey's Regular Unsweetened Cocoa and Hershey's Special Dark Cocoa. The Special Dark deepens the color of the cookie while the Regular Cocoa provides the lighter sweet cocoa flavor.