Lightly coat a 9x13" pan with cooking spray.

In a large saucepan, melt the butter over low heat. Once melted, add in the marshmallows. Stir until the marshmallows are completely melted.

Remove the saucepan from heat and add the Rice Krispies to the melted marshmallows. Add molasses, vanilla, ginger, cinnamon, allspice, nutmeg, and salt and gently stir the mixture until the cereal is completely coated in marshmallow.

Spoon the mixture into the prepared pan and gently press down using a lightly oiled rubber spatula. Don't press too compactly.

Let treats cool for about 5 minutes before using a lightly oiled gingerbread man cookie cutter to cut out shapes. Press remaining scraps together in the pan and continue cutting shapes until all of the mixture is gone.

Use mini M&Ms and melted white chocolate to decorate gingerbread men, if desired.