Heat oven to 350 F. Melt butter.
Crack an egg to a bowl with melted butter. Add brown sugar and vanilla extract. Beat until smooth.
Combine flour, hot cocoa mix, baking soda and salt together in a separate bowl.
Add in the ingredients from strep#2 (butter, sugar, egg and vanilla extract). Mix well.
Stir in chocolate chips.
Drop a tablespoon size dough about 2 inches apart onto a baking sheet with parchment paper. Bake for 10 minutes. (You can leave them in about 2 minutes more if you want them to be crunchy)
Remove pan from the oven and let the cookies cool down a bit before moving them to cooling racks.