1Preheat over to 350. In a large bowl, combine flour, sugar and egg. Cut in 1/2 cup of butter until crumbly. Stir in walnuts.
Reserve 2 cups of crumb mixture. Press remainder firmly on the bottom of a greased 9x13 baking pan. Bake 15 minutes.
2Meanwhile, in a heavy saucepan, over low heat, melt caramels with sweetened condensed milk and remaining 1/4 cup of butter. Pour over prepared crust. Top with reserved crumb mixture. Bake 2o minutes or until bubbly. Cool.
3Cut into bars. Store loosely covered at room temparature.