Make the oat layer. Combine oats, salt, maple syrup, SunButter and vanilla. Stir until well combined and press ⅔ of the mixture into the prepared pan and place in the fridge. Save the remaining ⅓ for the topping.
Make the fudge filling. Place the chocolate and SunButter in a microwave safe glass measuring cup or bowl and microwave until smooth and creamy- about 2 minutes, stirring every 30 seconds. Pour over the oats in the pan, spreading evenly and then top with remaining ⅓ oats, sprinkle on evenly and press gently in.