In a small saucepan over medium-low heat, combine peanut butter, brown rice syrup and vanilla, stirring occasionally, for 4–8 minutes. Heat until ingredients are softened and easily stirred. Pour peanut butter mixture over dry ingredients, and stir with a wooden spoon to mix very well. Pour mixture into prepared pan, and place a piece of parchment paper over top. Press down firmly and evenly on parchment with your hands to pack mixture into the pan. Chill for 30 minutes, slice into bars and wrap bars individually to store. Store in an airtight container in the fridge for up to 2 weeks or in a ziptop, freezer-safe bag for up to 3 months.