Combine sugar and butter in a large bowl. Stir in vanilla and egg. Combine flour, oats, 1/2 teaspoon salt, and baking soda in a bowl. Add oat mixture to sugar mixture and stir with a fork until crumbly. Press 3 cups mixture into bottom of a 13X9-inch pan coated with cooking spray.
Place milk, butterscotch morsels and 1/8 teaspoon salt in a bowl and microwave at HIGH 1 minute or until morsels melt, stirring 2 times. Stir in walnuts. Scrape mixture into pan, spreading evenly over crust. Sprinkle with remaining oat mixture, gently pressing into butterscotch mixture. Bake at 350 degrees for 30 minutes or until topping is golden brown. Run a knife around outside edge and cool. 36 servings. (Cooking Light)