Preheat oven to 350 degrees. Press pie crust firmly into a 9 inch pie plate.
In an electric mixer cream together butter and brown sugar until light and fluffy. Add egg and vanilla and mix until well combined. Mix in flour, cornstarch, salt, and baking soda until just combined.
Using a spatula, fold in the chopped candy.
Press into the pie crust. Bake for 25-30 minutes until golden brown.