Arrowhead Mills makes millet puffs, but you can also substitute other unsweetened puffed cereals, like Kashi 7 Whole Grain Puffs. Dried cherries, cranberries, or raisins can be used instead of currants. All of the spices are available at Amazon.com
Place the butter in a large skillet or Dutch oven; heat over medium heat until frothy.
Add the marshmallows and start to melt them, stirring with a rubber spatula so that they don't stick or burn (you can lower the heat if you need to). When the marshmallows are halfway melted, add all the remaining ingredients except the millet and stir well, so spices start to toast and are fully mixed with the marshmallow.
Add the millet, turn off heat, and stir until all of the millet is mixed and evenly coated in the spiced marshmallow mix.
Move the pan to a heat-proof surface, and immediately start rolling into small balls, about the size of a cherry; if your hands are slightly damp with cold water, the mixture will be easier to work with. Place the balls on a plate, uncovered, until they dry out slightly, about 1 hour. Store in an airtight container up to three days.