Preheat the oven to 400 degrees F (200 degrees C). Generously grease an 8 or 9 inch square pan.
In a large bowl, stir together vegetable oil and oats. Mix in brown sugar, corn syrup, salt, and vanilla. Press mixture into prepared pan.
Bake for 12 minutes in preheated oven. Set aside to cool.
Cut into 4 large squares to remove from pan. Cover with melted chocolate, and sprinkle with nuts, if desired. Allow the chocolate to cool, and then cut each square into 9 pieces.
