Add all ingredients EXCEPT rice bubbles in slow cooker, on high for 5 mins to melt.
Switch to low with lid off & stir with a metal spoon, every 10 mins for about 60 - 90 mins.
Add rice bubbles about 10 minutes before the end so they remain crispy!
When ready, pour into a 20cm tray lined with baking paper & melt 2 tablespoons of peanut butter in microwave for the top. (see picture it was a bit more than a drizzle!)
Put in fridge for 3 hrs or longer (If needed) to set, then cut into 16 squares.. Melts in your mouth!