In a large mixing bowl, cream together cannabutter and brown sugar.
Add in egg and vanilla and mix well. Add flour and baking soda and mix until completely incorporated. Fold in M & M's.
Spread batter into a 9-inch pie pan sprayed with nonstick cooking spray.Bake for 25-30 minutes, or until a toothpick comes out clean. Let cool and cut into slices.Top with a scoop of ice cream and drizzle of chocolate syrup.