Place a pan filled with water over a medium heat until it simmers. Put a glass or metal bowl on top and pop the marshmallows into the bowl.

Leave for 10 minutes or so, until the marshmallows begin to melt. Gently stir with a spoon until they've fully melted into a gooey mess.

Pour in the peppermint extract and a few drops of green food coloring, stirring all the time and adding more extract and coloring to get the right flavor and color.

Pour the melted marshmallow mixture into a small flat baking tray or dish and place in the fridge for at least an hour to set.

When set, sprinkle some icing sugar on top and use a heart or shamrock cookie cutter to cut out individual marshmallows.