In a large mixing bowl, begin by sifting the powdered sugar to remove any clumps, creating a smooth texture. Follow this by sifting the unsweetened cocoa powder into the bowl.

Add the powdered milk to the sifted ingredients. Using a whisk, mix thoroughly to ensure all components are evenly combined and form a uniform hot chocolate mix.

For an extra touch of sweetness and texture, you can add mini marshmallows to the mixture before storing. Transfer the prepared hot chocolate mix to an airtight container. It can be stored in the pantry for up to six months, making it a convenient treat for cold days.