Step 1

Preheat oven to 180C or 160C fan. Line a 28cm x 18cm slice tin with on-stick baking paper, extending over the two long sides.

Step 2

Empty contents of cookie mixture packet into a bowl and add nuts. Add butter and egg. Mix with a wooden spoon, and then your hands, to combine evenly. Press into tin, using the back of a spoon to smooth the surface. Bake for 20 mins or until golden brown. Cool in the tin.

Step 3

Place chocolate in separate bowls and microwave, one at a time, for 2 mins, or until soft. Stir until smooth. Drop spoonfuls of chocolates onto the slice, and use a skewer to create a marbled effect. Place in the fridge for 20 mins, or until set.

Step 4

Stand slice at room temperature for chocolate to soften slightly. Lift from the tin and cut into squares to serve.