Read recipe "note" to decide which step to add in the marshmallows.
Gently separate the oreos by slowly twisting them apart. (Some will break, it's okay, just try to be gentle)
Separate the white candy melts into 3 parts (this is to keep it from getting hard while you decorate) and place each section in a microwave safe bowl.
To make the chocolate easier to work with about 1/2 teaspoon vegetable oil to each section of chocolate (you can add more later if needed to thin it even more).
Melt in 20 second bursts in the microwave (Microwave 20 seconds, stir 20 seconds, etc.)
Be patient when melting and stir well in between bursts to avoid burning the chocolate.
Dip one end of the lollipop stick into the melted chocolate and press that side into the cream side of the oreo.
Place the other half of the oreo on top and gently press and hold.
Place the oreo on top of a fork over the bowl of melted chocolate. Use a spoon to spoon chocolate over the oreo.
Shake the fork gently on the edge of the bowl until the chocolate forms an even layer.
Set aside on a sheet of parchment paper.
Add two marshmallows to the top and hold to secure. Press a white candy melt on the oreo and then using melted white chocolate, attach the miniature M&M to that candy melt.
Allow the chocolate to mostly harden (or harden all the way if you want the eyes to stand out more) and then pipe on 2 dots for eyes.
Notes
In the video I add the miniature marshmallows "ears" before dipping in chocolate. You can do this to keep the marshmallows fresh, but I did find it easier to add the marshmallows AFTER dipping in chocolate. If you are making these way in advance though, dip the marshmallows to keep them soft and edible.