Add whole milk, heavy cream, sugar, and cocoa powder. Whisk well to combine. Using the sauté setting, cook hot chocolate in the Instant Pot for 5-6 minutes, or until it warms through.
Pour your hot chocolate into mugs and top with mini marshmallows.
Notes
Topping options: There are endless options for hot cocoa toppings! You can add homemade whipped cream, mini marshmallows, mini chocolate chips, chocolate shavings, caramel syrup, chocolate syrup, etc.
For a thicker and richer drink: If you want to make your hot cocoa richer and thicker, replace 1 cup of whole milk with heavy cream.