Step 1

Line a 20cm square cake tin with baking paper, allowing for some overhang to make it easy to lift out the finished slice. Place Lattice biscuits shiny side down in a single layer in the base of the tin. You may need to cut some so they fit snugly.

Step 2

Sprinkle the gelatine over 1/3 cup cold water in a small jug or shallow bowl. Use a fork to gently whisk. Leave to soften.

Step 3

Place cream, milk, vanilla and sugar in a medium saucepan, and bring to a simmer. Remove from heat and whisk to ensure sugar has dissolved. Add food colouring until you reach the desired colour. Add softened gelatine mixture and whisk to combine.

Step 4

Allow to cool to room temperature, whisk again briefly, then refrigerate for 30 minutes. The mixture should be starting to set. Pour a small amount - approximately half a cup - into prepared tin over the biscuits and use a spatula to smooth out evenly. Once set, this will form a seal over the biscuits. Return both the tin and the remaining mixture to the fridge for a further 30 minutes to set further. When it is slightly thicker and has a wobble when you shake the bowl, whisk again thoroughly to ensure even distribution of the colour, then pour the entire contents into the tin. Arrange more Lattice biscuits in a single layer on the top, this time with the shiny side up. Return to the fridge for another 2 hours to set fully.

Step 5

Use overhanging baking paper to gently lift the slice from the tin. Slice into squares and serve.