Preheat oven to 180°C. Line 8 holes of a 1/3-cup (80ml) muffin pan with paper cases. Sift the flour, baking powder and bicarbonate of soda into a medium bowl. Stir in 1/2 cup (110g) caster sugar. Add the milk, 100g of the Flora Plant Original and 2 tsp vanilla. Whisk until smooth. Spoon evenly among the paper cases. Bake for 20-25 mins or until a skewer inserted in the centres comes out clean. Transfer to a wire rack to cool completely.
Use an electric mixer to beat the icing sugar, 125g of the remaining Flora Plant Original and the remaining vanilla in a bowl until pale and smooth. Transfer to a piping bag fitted with a 1cm fluted nozzle.
Line a baking tray with baking paper. Place golden syrup, remaining caster sugar and remaining Flora Plant Original in a saucepan over medium heat. Bring to the boil. Reduce heat to low. Cook for 5 mins or until mixture thickens. Remove from heat. Stir in popcorn and 2 tbs sprinkles. Cool slightly. Divide the mixture into 8 portions. Shape into balls. Place on the lined tray to set.
Pipe icing onto the cupcakes. Top with caramel popcorn and remaining sprinkles.