If you'd like to toast your marshmallows, preheat oven to 400° and line a baking sheet with parchment paper. Spread the marshmallows evenly on the prepared baking sheet and bake in the preheated oven for 5-6 minutes, or until browned and crispy (do not burn). Set aside.
Add the half & half and marshmallows to a medium saucepan and heat over low heat, stirring frequently. Continue to heat until the marshmallows are melted and the mixture is smooth.
Add remaining ingredients and continue to stir until everything is combined, dissolved, and smooth. Remove from heat. Note: the mixture will be foamy, but the foam will dissolve as it cools.
Allow the creamer to cool at room temperature for 15 minutes, then transfer to a mason jar and store in the fridge for up to 2 weeks.
Notes
This recipe makes about 2.25 cups of s'mores creamer!