Preheat your oven to 150ºc and line the base and sides of a 20cm round cake tin with baking paper.
Place the butter, white and caramello chocolates into your Thermomix bowl and add 200 grams of water. Cook for 3 minutes, 60 degrees, speed 2 or until the mixture is melted and has combined.
Add 200 grams of the Caramel Top n Fill to the melted ingredients, along with the brown sugar and vanilla extract. Mix for 20 seconds, speed 5 before scraping down the sides and mixing for a further 10 seconds, speed 5
Add the eggs, plain flour and self raising flour and mix for 10 seconds, speed 5 to combine. Scrape down the sides of your Thermomix bowl and mix for a further 10 seconds, speed 4 to ensure the mixture has been combined well.
Pour the mixture into cake tin you prepared earlier and cook for 1hr and 15 mins, or until a skewer inserted into the middle comes out with moist crumbs on it.
Once the cake has cooled completely top it with the remaining Caramel Top & Fill and decorate with caramel popcorn.