Add all ingredients to a medium bowl and whisk until combined. If you're making this as a gift, I like the look of layering the chocolate chunks on top of the hot cocoa mix, however it's less practical this way - you do you! Place DIY hot cocoa mix into an airtight container.
1 cup whole milk powder, ½ cup cocoa powder, ½ cup cane sugar, ½ tbsp arrowroot starch, ¼ tsp kosher salt, ¼ cup unflavored collagen peptides, 2 oz dark chocolate