Toffee Bars

crust: nonstick cooking spray 1/2 c. brown sugar blend splenda 4 T. unsalted butter, room temperture 1 large egg yolk 1 c. all purpose flour 1/4 t. salt
toffee layer: 1 c. brown sugar blend splenda 1/2 c. light corn syrup 1/2 c. evaporated milk 4 T. unsalted butter room temperture 1 1/2 t. vanilla
Preheat oven to 350. To make crust beat the splenda and butter until mixed. Add egg yolk and beat until combined. On low gradually beat in flour and salt, beat just until mixture forms fine crumbs. Lightly spray a 13x9 pan with nonstick spray. Press dough evenly over bottom. Bake until crust is golden brown about 12 minutes. For filling combine remaining ingredients except vanilla in a heavy saucepan. Cook over medium heat over medium heat stirring often until mixture reaches 265 on candy thermometer, about 10 minutes.Stir in vanilla. Spread over crust. Bake about 10 minutes or until bubbling throughout. Let cool 5 minutes before cutting.