Chocolate Walnut Crumb Bars

From Carole Larsen.

1 cup butter (softened)
2 cups flour
½ cup sugar
¼ teaspoon salt
1 ½ cups chocolate chips
1 (14 oz) can sweetened condensed milk
1 teaspoon vanilla
1 cup chopped nuts
½ cup chocolate chips

Beat butter in bowl until creamy.

Add flour, sugar, and salt to butter. Beat until crumbly. With floured fingers, press 2 cups crumb mixture into bottom of greased 9x13 pan (reserve remaining mixture). Bake at 350˚F for 10-12 minutes or until edges are golden brown.
Warm chocolate chips and sweetened condensed milk in small, heavy saucepan over low heat, stirring until smooth.

Stir vanilla into chocolate mixture. Spread over hot crust.

Combine nuts and chips and stir into reserved crumb mixture. Sprinkle over chocolate filling. Bake at 350˚F for 24-30 minutes or until set. Cool in pan or wire rack