Into a food processor, pulse together the All-Purpose Flour (1/2 cup), Caster Sugar (2 tablespoon), and Butter (120 gram). Then add in your Egg (1) and Water (1 tablespoon). Combine everything well.
Kneed the dough on a floured surface until it is nice and smooth. Then, wrap the dough in a kitchen plastic paper, and pop it into the fridge for about 30 minutes.
Using a rolling pin, flatten your dough until it is thin in thickness. Then, using your tart tins, cut out circular shapes from the dough, and press them into separate tart tins. Cover each tin with a baking paper, and bake under 180 degrees C (350 degrees F) for about 15 minutes.
Into a sauce pan, melt the Caster Sugar (3/4 cup) for about 5 minutes.
To the melted sugar, add in the Whipping Cream (2/3 cup), and cook the mixture for about 2 minutes while stirring.
Add in the Butter (100 gram) and keep on stirring until everything is combined. Then pour the filling mixture over each tart, and pop them into the fridge for about 6 hours.