Base:
2 1/4 cups flour
1/2 cup superfine sugar
3/4 cup sweet butter, softened
Filling:
7 TBSP butter, diced
1/2 cup light brown sugar
2x 14 oz. cans sweetened condensed milk
Topping:
3 1/2 oz. semisweet chocolate
3 1/2 oz. milk chocolate
2 oz. white chocolate
1. Preheat the oven to 350. Line and lightly grease a 13x9 jelly roll pan. Put the flour and sugar in a bowl and rub in the butter until crumbly. work until it forms a dough.
2. Put dough in prepared pan and press it down. Prick all over with a fork and bake for 20 minutes of until light brown. Cool.
3. Put butter, brown sugar and condensed milk into a pan and heat gently, stirring until the sugar has dissolved. Stirring constantly, bring to the boil. Reduce heat and simmer for 5-10 minutes until thickened and turned a caramel color. Remove from heat.
4. pour the filling over the base and leave until cold.
5. Melt each type of chocolate separately in a microwave. Spoon lines of semisweet and milk over the set caramel. Add small spoonfuls of white chocolate. Use a skew to form a marbled effect on the top.