Pass confectioner’s sugar, cocoa powder, and cornstarch through a fine mesh strainer.

Discard any lumps or hard bits of sugar.

Whisk in the dry milk powder.

Stir in dehydrated mini marshmallows, if using.

Transfer cocoa mix to an airtight container or large food storage bag. Store at room temperature for up to 6 months.

 To Serve:

 Place 3 tablespoons homemade hot cocoa mix in the bottom of a mug. Add 180 milliliters (6 fluid ounces) boiling water or milk and stir to combine. Top with vanilla marshmallows, shaved chocolate, whipped cream, or other toppings as desired.