Cream the butter, granulated sugar, and brown sugar together with an electric mixer until light and fluffy.
In another bowl, whisk together the flour, hot chocolate mix, baking soda, and salt. Set aside.
Beat the eggs and vanilla into the butter mixture.
Slowly add in the dry ingredients, scraping down the sides of the bowl as needed.
Combine the white chocolate, milk chocolate, and semisweet chocolate chips.
Add the chocolate chips to the cookie dough and mix on low until combined. Refrigerate the dough for 1 hour.
Preheat the oven to 350°F. Drop balls of dough onto 2 parchment-lined baking sheets. A cookie scoop will make quick work of this.
Bake the cookies until the edges are lightly browned, 9 to 11 minutes. Let cool for 5 minutes before removing from the pan. Cool on a rack and serve warm or room temperature.
Pour yourself a big glass of milk if you like, then sit down for a treat. Enjoy!