Line a 23cm x 13cm loaf pan with baking paper or lightly grease with cooking spray.
Place rolled oats in food processor and pulse until oats are a floury consistency.
In a medium bowl, mix processed rolled oats with quick oats, protein powder and rice puffs.
In a small pan over medium heat, stir honey, peanut butter and coconut oil until melted and combined. Remove from heat and stir in vanilla extract. Pour peanut butter mixture over oats. Stir well.
Using wet hands, press mixture into prepared loaf pan.
In microwave, melt the chocolate for 1 minute, and then 30-second intervals stirring in between, until fully melted. Use a fork to drizzle chocolate over slice.
Let cool in refrigerator for 30 minutes before slicing into 12 pieces.