2 sheets pre-made puff pastry
6 small lady finger bananas
80g soft brown sugar
70g butter, chopped
1 tbsp treacle
2 tbsp custard powder
½ cup milk
½ tsp vanilla paste
Salted Butterscotch Sauce
225g soft brown sugar
125ml single cream
2 tbsp golden syrup
1 tsp sea salt crystals
Preheat oven to 220°C. Cut pastry sheets in half into 4 rectangles, about 10 x 20cm. Place on a slightly wet baking sheet. Prick, very lightly, with a fork. Leave to relax, covered, for 20 minutes. Cover with a piece of baking paper and bake for about 15 minutes or until brown and puffed.
Carefully, split each piece of pastry in 2 horizontally and return to the oven, cut side up, to dry out for 3 minutes. Leave to cool on a wire rack.
To make butterscotch custard combine sugar, butter, 2 teaspoons water and treacle in a medium saucepan. Stir over low heat until sugar is dissolved.
Mix custard powder and milk together then add to the saucepan. Stir until the mixture boils and thickens. Remove from heat and whisk in vanilla paste. Cover and cool until you are ready to use it.
Choose the piece of pastry with the smoothest base, and place on a serving platter. Spread with a small amount of butterscotch custard and arrange slices of banana over the top. Place a second piece of pastry on the top. Press down gently but firmly. Repeat with the layers of pastry, bananas and butterscotch custard until all the pastry layers have been used. Finish with a whole piece on top.
To make the salted butterscotch sauce, in a non-stick saucepan over medium heat heat brown sugar, cream, butter, golden syrup and salt just to boiling point, stirring occasionally.
Top mille-feuille with some thinly sliced bananas and then a drizzle of the butterscotch sauce. Use a sharp knife to cut into four pieces, serve.