Make rice crispy treats in the microwave by microwaving 3 tablespoons of butter and 1 package of large marshmallows in a large bowl for three minutes. Immediately stir the mixture, and then fold in 1 box of rice cereal and 1 bag of M&Ms. Spread the gooey treats into the bottom of a rimmed baking dish, and chill it for 20 minutes before cutting it into bars and serving.
Another option is to make a single serve microwave rice crispy treat by adding 4 large marshmallows and 1 tablespoons of butter in a mug and microwaving the mixture for 30 seconds. Once everything has melted, stir the mixture, and add in 1 cup of crispy rice cereal. Eat the treat hot or cold.
To add a Milky Way flair to simple microwave rice crispy treats, melt 1 bag of mini marshmallows and 6 tablespoons of butter in a bowl in the microwave. Stir the mixture until it has a smooth texture, and add in 1 teaspoon of vanilla extract. Fold in 5 cups of rice crispy cereal, and spoon the mixture into a greased baking sheet. Melt together 14 ounces of caramel candies, 6 tablespoons of butter and 1 can of sweetened condensed milk, stirring often, and pour the mixture over the treats.
Refrigerate the rice crispy bars for 10 minutes. Meanwhile, melt 2 cups of chocolate chips in the microwave, and pour it over the caramel layer. Allow the chocolate to harden before cutting and serving the treats.