Spray a 7x11" baking dish with non-stick spray. Set aside.
In a large saucepan, melt butter, molasses, cinnamon, and ginger together over low heat. Add marshmallows and stir until completely melted. Remove from heat. Add Rice Krispies cereal and stir until well-coated.
Using a spatula sprayed with non-stick spray, gently press mixture into baking pan. Allow to cool completely before cutting into squares or into desired shapes with a cookie cutter.
SPICED WHITE CHOCOLATE DRIZZLE
In a microwave safe bowl, melt the white chocolate in the microwave in 15 second increments on HIGH, stirring after each session until completely smooth. Stir in cinnamon and ginger.
Pour melted chocolate into a large plastic bag with the corner snipped off, a decorating bottle, or a piping bag fitted with a small decorating tip. Drizzle the white chocolate onto the cut treats. Allow chocolate to set before serving or storing. Store treats in an airtight container up to one week.