• Prepare a 9x13-inch baking pan by spraying it with nonstick cooking spray or greasing it with butter.
• In a large saucepan over low heat, melt the butter completely.
• Add the marshmallows and vanilla extract to the saucepan and stir until melted and well-combined. Continue to stir and cook for another 2 minutes. Remove the marshmallow mixture from the heat.
• Stir in the cereal and toss until well-coated.
• Transfer the cereal mixture to the prepared pan and use a piece of waxed paper or a buttered silicone spatula to firmly pack it into an even layer. Set aside and allow the bars to cool to room temperature for an hour (or 15 minutes in the fridge).

Decorating the Santas

• Meanwhile, heat the red melting chocolate according to the package directions. Add 1/2 tablespoon of vegetable oil to thin the chocolate slightly and stir.
• Repeat this process with the white melting chocolate.
• Once the Rice Krispie bars are cool enough, cut the treats into 10 rectangles.
• For each Santa: quickly lower the top 1/2 inch of the treat into the melted red chocolate and the lower 1/3 of the treat into the white chocolate, leaving an uncovered space in between. Let the excess chocolate drip back into the bowl, then set each treat aside on a sheet of waxed paper or parchment paper.
• While the chocolate is still wet, sprinkle the red section with red sanding sugar and the white section with coconut flakes (or white sanding sugar or sprinkles if you don't like coconut).
• Place the remaining white chocolate in a piping bag. Snip the very end and pipe a thick line of white at the bottom of the red section. Sprinkle it with coconut.
• Use a dot of white chocolate to adhere the candy eyes and red candy nose in the undecorated section of the treat.
• Set aside and let the chocolate set for about 15 minutes before serving.