Pistachio Brownie Toffee Bars Recipe

Preheat oven to 350 °. In a large bowl, cream butter and brown sugar until light and fluffy. Beat in egg yolk and vanilla; gradually add flour to creamed mixture, mixing well. Press dough onto bottom of a greased 15x10x1-in. baking pan. Bake 12-14 minutes or until golden brown. Meanwhile, in a large bowl, combine brownie mix, water, oil and egg until blended. Spread brownie batter over hot crust. Bake 14-16 minutes longer or until center is set. Cool completely in pan on a wire rack. Spread melted chocolate over bars; sprinkle with pistachios. Let stand until set. Cut into bars.