In a small saucepan (non stick if possible) heat up the brown rice syrup and butter. Simmer for a two minutes, stirring the entire time.
Add Rice bubbles to a large mixing bowl and pour Syrup mix over the top. Mix together well. You can add the Vanilla at this stage for a more Vanilla tasting slice. (like the store bought variety :)
Spread the Mix out onto the baking tray and press down to flatten in the tray. Rice bubbles should be firmly compressed into the pan as this gives your slice more structure later on.
Place in Fridge (or freezer) until firm, then cut into snack size squares.
Notes
If you are packing it for school, make sure the lunch box is chilled or the slice may get a little bit melted and sticky.
This slice will set very firm when cool and remain quite in shape when out of the fridge
Store in an airtight container in fridge or the freezer if you are packing in a school lunch.