Process all ingredients in food processor and press into 22cm square slice tin.
Bake until golden (approximately 20 minutes in a moderate oven).
To make caramel:
Combine all ingredients in a microwave-safe bowl and cook in microwave on high for approximately 3 minutes. Give it a good stir and place back in for 2 minutes.
Stir, pour on top of base and cook in oven for approximately 10 minutes (until bubbly).
To make marshmallow:
Combine all ingredients in microwave-safe bowl and cook on high for 4 minutes. Remove and whisk. Cook for a further 3 minutes or until bubbling. Whisk. Beat with hand-held beaters until thick and glossy. Place on top of caramel and place in fridge.
You can roast some coconut and sprinkle that on top for decoration or melt some chocolate and drizzle it on top.