In a large bowl, cream sugar and butter until light and fluffy. Beat in vanilla and eggs. Combine the flour, baking soda and salt; gradually add to creamed mixture. Stir in oats by hand. Press two-thirds of mixture into a greased 15x10x1-in. baking pan.
For filling, heat butter, milk and chocolate chips in a saucepan over low heat, stirring constantly, until chocolate is melted. Remove from heat; stir in the nuts, vanilla and salt. Spread over oat mixture in pan.
Drop reserved oat mixture by teaspoonfuls onto filling. Bake at 350° for 25-30 minutes. Cut into bars while warm.