1/4 cup butter
Food Coloring (however many drops it takes to reach your desired color)
Just double this recipe and make one batch red and one batch green. Feel free to add in any type of decorative sprinkle or candy.
Melt butter and marshmallows together; remove from heat (this is when you would stir in your food coloring). Add Rice Krispies (also add candies or sprinkles now, if using) and stir until Rice Krispies are well coated.
Press into a greased 9 x 13 pan. Cool and cut into squares.