Grease a large tube or Bundt cake pan with 2 teaspoons of the oil. Set aside.
In a large bowl, mix the popped corn with the M&Ms and the peanuts and set aside.
In a medium saucepan, melt the butter, the remaining 1/4 cup vegetable oil, and the marshmallows over medium-low heat, stirring occasionally. When melted, use oven mitts or pot holders to remove saucepan from heat and pour marshmallows over the popcorn mixture. Stir to combine.
Spoon mixture into the prepared cake pan. Using your hands or the back of a spoon, press firmly so that the mixture is compacted.
Cover with aluminum foil to keep moist. Let sit for about 3 to 4 hours, or until firm and set.
To serve, invert the cake pan onto a large plate or platter. Shake gently to release the cake. Serve at room temperature.
YIELD: 1 cake, serving 12 to 16