In a mixing bowl, cream the butter, brown sugar, and sugar until light and creamy, about 5 minutes.
Beat in the eggs and vanilla.
In a separate bowl, whisk together the flour, cocoa, baking powder, and salt. Add to the mixer and beat until well mixed.
Fold in the mini chocolate chips and about ¼ cup silver sanding sugar.
Using a cookie scoop, portion the cookie dough into balls. With half of the cookie dough balls, dip in remaining silver sanding sugar and press three to four plain chocolate chips (from the disco chocolate chips) into the top of the cookies. With the other half of the cookie dough balls, press three to four glittered chocolate chips into the top of the cookies.
Bake for 10 minutes before removing from the oven. Allow the cookies to cool completely on the baking sheet as they will continue to cook from the residual heat.
Store in an airtight container for up to one week.
You can use other types of sprinkles or crystalized sugar if you prefer.