Preheat oven to 350 degrees and line an 8×8 inch baking dish with parchment paper.
Place softened butter, brown sugar, pumpkin, egg and vanilla into a large mixing bowl, stirring to combine. Stir in flour, salt, candy corn pieces and peanuts. Transfer to lined baking dish. Bake for 25-28 minutes, until baked through. Remove and let cool for 20 minutes.
To prepare icing, whisk powdered sugar and cream until smooth. Drizzle over warm bars.