In a microwave safe bowl, heat chocolate chips, sweetened condensed milk and hot chocolate in 30-second increments, stirring after each, until completely melted and combined (around 2-3 minutes).
Pour fudge into parchment lined pan, smooth into a flat layer, and top with mini marshmallows (lightly press on top of the marshmallows to set them into the fudge mixture). Optional: you can also top the fudge with crushed candy cane bits or mini chocolate chips as well!
Chill in the refrigerator until set (about 2 hours) and then cut into squares.