Melt marshmallows with the milk over low to medium heat. Add the extract and food coloring. Cool in the refrigerator until mixture mounds off a wooden spoon. Fold together with whipped topping and pour into the graham cracker crust. Chill thoroughly. Sprinkle crushed peppermint candy over top of pie just before serving. Variation: Grasshopper Pie Substitute regular mint extract for the peppermint extract. Use green food coloring. Pour into a chocolate cookie crust and top with shaved chocolate.