Combine Ingredients: In a medium-sized saucepan, add the chocolate chips, brown sugar, pumpkin pie spice, and milk.
Heat Mixture: Place the saucepan over medium-high heat on the stovetop. Heat gently while whisking to ensure the chocolate chips melt evenly and do not stick to the bottom, about 3-4 minutes. Do not bring it to a boil or a simmer.
Remove from Heat: Once steam is visible off the surface, remove the saucepan from the heat.
Serve: Pour the hot chocolate into mugs and top with marshmallows and a dusting of pumpkin spice. Enjoy!
Notes
Store leftovers: Allow the hot chocolate to cool completely before transferring it to an airtight glass jar, such as a mason jar, or a sealed container. Store it in the refrigerator for 2-3 days.Make it in advance: You can also prepare the hot chocolate ahead of time using the same storage method above.Reheat: In a saucepan on the stovetop over low-medium heat. Be sure to whisk it well to recombine any ingredients that may have settled, heating it up to your preferred temperature.