Line a 18 x 28cm slice tin with baking paper and set aside until needed.
Place the butter, brown sugar and honey into your Thermomix bowl and cook for 10 minutes, 100 degrees, speed 1.
Add the vanilla extract and mix for 10 seconds, speed 5.
Scrape down the sides of your Thermomix bowl and add the rolled oats, puffed rice and cinnamon. Mix for 15 seconds, speed 5, reverse. Scrape down the sides and base of the bowl and mix for a further 10 seconds, speed 5, reverse to ensure the mixture is well combined.
Pour the mixture into your prepared slice tin and use the back of a spoon to push it firmly down to flatten the surface.
Sprinkle the chocolate chips over the top of the slice and gently press them into the slice.
Transfer to the fridge to chill for six hours (preferably overnight) before cutting into bars.