Preheat the oven to 350 degrees F.
Beat the margarine and brown sugar until light and fluffy.
Add the walnuts and flour; mix well.
Reserve 1/2 cup of the crumb mixture; press the remaining crumb mixture into bottom of a 8? square pan.
Bake at 350 degrees for about 10 minutes.
Combine the softened cream cheese, granulated sugar and vanilla; using an electric mixer, mix at medium speed until well blended. Add the egg; mix well.
Layer 1/2 cup of the Smarties or M&M candies over the crust; top with the cream cheese mixture.
Combine the remaining candy and reserved crumb mixture; mix well.Sprinkle the crumb mixture over the cream cheese mixture.
Bake at 350 degrees for about 20 minutes.Let cool completely before serving