Cream butter and sugar. Mix in eggs and vanilla extract. In a separate bowl, sift flour, baking soda and salt together. Stir in oats. Add creamed mix to dry ingredients. Stir well and set aside.
Melt chocolate chips in saucepan. Over low heat, stir in condensed milk, butter and salt. Add walnuts and vanilla. Spread 2/3 of oat mix in 9"x13" pan. Cover with chocolate mix. Dot with remaining oat mix and swirl. (Chocolate will not all be covered.) Bake at 350 degrees for 25 min. until top is browned. Let cool and cut into bars.
Quick, easy and sturdy, these bars travel well so they're a good choice if you're sending baked goods through the mail.