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I recommend starting with plain M&Ms, or a plain variation, instead of some of the filled M&M's, like peanuts or pretzels. Remove them from the packaging and place them on a small microwave-safe plate. Set the microwave for 40 seconds. This should be enough for a regular package of M&M's, but you might need a few more seconds if you do a larger quantity.
After they're finished, you might notice that some of the candy shells have cracks, but that's okay. As soon as you bite into them, the shell cracks open and a flood of warm melted chocolate comes pouring out. The combination of crunchy shell and liquid chocolate is really good. This method of microwaving your M&M's can elevate even relatively unexciting candies, like plain M&M's, into delicious treats.