Preheat oven to fan forced 180ºC. Line a 20cm square pan with baking paper ensuring edges along one side come up over the top of the pan for easy removal.
Place macadamia nuts into Thermomix bowl and coarsely chop by setting dial to closed lid position and pushing the Turbo button ONCE. Set aside.
Place remaining base ingredients into Thermomix bowl and process for 7 seconds on speed 6 until mixture resembles breadcrumbs.
Press into lined tin. Spread the macadamia nuts over the top of base.
Make topping by placing butter, sugar and vanilla into Thermomix bowl and cooking for 3 minutes at 60ºC on speed 1.
Cook a further 6 minutes at 100ºC on speed 3. Pour mixture over base and bake for 20 minutes until caramel is bubbling.
Remove from oven and sprinkle immediately with chocolate chips. When they have begun to melt, use a metal spatula to spread evenly over the top.
Leave to cool in tin and using very sharp knife, slice into squares when cold.