Heat oven to 450 degrees. Grease 15x10 inch pan. Combine oats, sugar, margarine, corn syrup, vanilla and salt; mix well. Firmly press mixture into pan. Bake 12 minutes, or until mixture is brown and bubbly. Cool completely.

In saucepan over low heat, melt chocolate and shortening, stirring constantly until smooth. Spread evenly over oat base; sprinkle with nuts. Chill until set, cut into bars. Yield 60 bars.