Preheat the oven to 160ºC.
To make the tart cases: cut out 12 x 8cm rounds from the tortilla wraps using a plain round 8 cm cutter. If you don't have a cutter, you can use a round 8cm glass and cut around it using a small sharp knife.
Use the rounds to line the bun tin, pressing into each hole. Place a small square of greaseproof paper on top of each round then pour in the ceramic baking beans in each tart case to hold them down whilst baking. If you haven't got ceramic baking beans, you can use something else such as dried beans, uncooked rice or just some scrunched up foil to do the same job.
Place the lined bun tray in the preheated oven for about 5 minutes until the tart cases are lightly golden.
Remove from the oven and lift out the greaseproof paper and ceramic baking beans. Place the tart cases on a cooling rack and leave to cool.
To make the butterscotch filling: place the reduced fat spread, soft light brown sugar, brown granulated sweetener, vanilla essence and butterscotch flavouring in a small saucepan. Place over a low heat and stir for about 5 minutes until just dissolved. Remove from the heat as soon as it has dissolved. Don't let the mixture bubble or boil.
Place the cornflour in a small bowl and mix with 1 tbsp of the milk, until smooth.
Pour the remaining milk into the melted reduced fat spread, sugar, sweetener, vanilla essence and butterscotch flavouring and stir. Place back on a medium heat and stir in the cornflour mixture, stirring constantly with a wooden spoon or balloon whisk.
Keep stirring and cook gently for about 4 - 5 minutes, until smooth, glossy and thickened. Don’t overheat and boil the mixture otherwise it may burn.
Place 1 1/2 tsp of the butterscotch filling in each tart case and spread out a little by tilting the cases.
Leave to cool and set for about 30 minutes.
Serve alone or with an accompaniment of your choice such as custard, or serve with a selection of other tea time biscuits and cakes.