In a large pot, melt butter and mini marshmallows over medium low heat. Stir these constantly so they do not burn.
Remove from heat right before the last marshmallows melt.
Add in rice cereal and use a spatula to fold the marshmallow mixture into the cereal. Continue until everything is incorporated.
Let sit 10-15 minutes to cool just slightly so that you can easily form the nexts with your hands.
To form the nests, butter your hands (yep, use butter like lotion) and then grab a tennis ball sized amount of krispie mixture and make a ball. Press your thumb into the center to make the indent of the nest and form the outsides as needed.
Place on parchment lined cookie sheet and repeat with remaining mixture, rebuttering your hands as needed.
Allow to cool. Once cool add egg shaped M&M's to the nest
Servings will vary on size of nests made.
You may also use muffin tins to make the next shape. I found by hand the easiest.