Chocolate Oat Squares

Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13 inch pan. In a medium bowl, cream together 1 cup butter with brown sugar until smooth. Beat in the eggs and 2 teaspoons vanilla. Stir in the oats, flour, baking soda and 1 teaspoon of salt. Press two thirds of the mixture into the bottom of the prepared pan. Set aside remaining dough. In a large saucepan over medium heat, combine the condensed milk, 2 tablespoons of butter, chocolate chips and remaining 1/2 teaspoon of salt. Stir frequently until melted and smooth. Remove from the heat and stir in walnuts and remaining 2 teaspoons of vanilla. Spread over the prepared crust and sprinkle with the reserved crust mixture. Bake in the preheated oven for 25 minutes, or until golden brown. Cool completely before cutting into squares.