Peggy Honey's English Toffee Bars

1 cup soft butter
1 cup brown sugar
1 egg
1 tsp. vanilla
2 c. flour
1/4 tsp. salt
6 oz semi-sweet chocolate chips
chopped walnuts
Cream butter and brown sugar. Add egg and vanilla and mix well. Stir in flour and salt then spread in a greased 9 x 13 baking pan. Bake at 325 degrees for 15 minutes until lightly brown around the edges. Remove from oven, sprinkle with chocolate chips and spread when soft enough. Sprinkle with chopped walnuts. Cool completely and cut into 2 inch squares.