Line an oven tray with baking paper, ensure the paper goes up and over the sides of the tray and set aside.
In a small saucepan, combine the sugar and the water over medium heat. Stir to dissolve the sugar.
Once the sugar has dissolved, increase the heat to bring a boil and leave until the mixture turns caramel in color.
Remove from the heat so the bubbles subside and stir in butter until it melts. Pour mixture onto your prepared tray and set aside to completely cool.
Once fully cooled, break toffee into pieces. For the ice cream tart
Grease a 22cm (9 inches) round loose-based fluted flan pan, set aside.
Melt 100g of the butter in a small saucepan over low heat.
Process biscuits until fine then pour in the melted butter and process until combined.
Press biscuit mixture into the base and side of your prepared pan, ensure it is compact, refrigerate for 15 minutes to set.
Place the ice-cream in a large bowl and beat it with a wooden spoon until barely softened. Spread ice-cream on top of your biscuit base in the pan, using a spatula to create a smooth surface. Loosely cover and leave to freeze overnight
Dice the remaining 75g butter and place in a medium saucepan with sugar. Over high heat, stir the mix until smooth. Pour in the condensed milk and golden syrup and bring it up to boil, stirring constantly. Allow the mix to boil for 10minutes, keep stirring to avoid the mix sticking. You will see it will thicken and turn caramel color
Remove from the heat and leave to rest for 10 minutes.
Whilst resting, slice the bananas thickly and arrange these in your cake tin on top of the ice cream. Layer on the toffee pieces. Carefully remove the cake from the tin.
Now stir the milk into the warm caramel sauce and drizzle over the top of your cake and serve immediately.