1. Preheat the oven to 325 degrees.
2. In the bowl of a stand mixer, cream together butter with the granulated and light brown sugars. Add the pumpkin puree and eggs and mix well. Sprinkle with pumpkin pie spice and mix well.
3. With the stand mixer running on low, add the flour a little at a time until fully incorporated. Use a rubber spatula to scrape down the sides of the bowl to ensure that it mixes completely.
4. Fold the M&Ms into the batter. Pour into the graham cracker crust, using the spatula to spread into one even layer. (
I like to place the pie crust on a baking sheet because it’s easier to get in and out of the oven this way.)
5. Bake the pie for 50-55 minutes, until a toothpick inserted into the center of the pie comes out clean.
6. The pie is best served warm with vanilla ice cream.