Melt margarine, oil, and marshmallows in a large saucepan over low heat, stirring constantly until smooth.

In a very large bowl, combine peanuts, M&M's, and popped popcorn.

Pour the melted marshmallow mixture over the popcorn mixture.

Gently fold the ingredients together until the popcorn is evenly coated.

Grease a 10-inch angel food cake pan.

Pour the popcorn mixture into the prepared pan and press down firmly to create an even layer.

Refrigerate for at least 2 hours, or until the cake is firm.

Loosen the edges of the cake from the pan with a spatula.

Invert the cake onto a serving plate.

Cut into slices with a serrated knife and serve.