In a large bowl, beat the cookie mix, brown sugar, butter and vanilla until mixture resembles coarse crumbs. Add egg and mix well.
Spread into a greased 13-in. x 9-in. baking pan. Bake at 350° for 12-15 minutes or until lightly browned.
Sprinkle with chocolate chips; let stand for 5 minutes. Spread chocolate over bars. Sprinkle with nuts. Let stand until chocolate is set. Cut into squares, then cut in half to form triangles. Store in an airtight container.