Step 1

Preheat oven to 180C/160C fan forced. Grease a 16.5 x 26.5cm (base size) slice pan and line with baking paper, allowing the paper to overhang the sides.

Step 2

Combine the Weet-Bix, flour, sugar and coconut in a large bowl. Make a well in the centre. Add the melted butter and stir until combined. Transfer to prepared pan then use the back of a spoon to press and spread mixture firmly over base. Bake for 15 minutes or until light golden. Set aside to cool completely.

Step 3

To make the topping, whisk together custard powder and 60ml (1/4 cup) milk in a medium saucepan until smooth. Stir in the remaining milk. Add the cream and condensed milk and stir until well combined. Place over medium-low heat and cook, whisking slowly then more vigorously as mixture thickens and comes to a simmer, for 10 minutes or until thickened. Cook, stirring constantly, for a further minute. Add the butter and vanilla. Whisk until combined.

Step 4

Pour the custard mixture into a heatproof bowl. Set aside, stirring often, until cooled slightly. Spoon into prepared pan and smooth the surface. Cover the surface with plastic wrap and place in the fridge for 2 hours or until set.

Step 5

When ready to serve, sprinkle slice with hundreds and thousands (see note). Slice into triangles to serve.