For the base, line an 18cm/7in square tin with parchment paper and set aside.
Melt the plain and milk chocolate, butter and honey in a small pan over a gentle heat. Stir occasionally until smooth and remove from the heat.
Meanwhile place the digestives in a plastic bag and roughly crush into pieces. Stir the biscuits into chocolate mixture gently and evenly. Add the Maltesers to the mixture, spoon into the prepared tin and smooth the surface. Chill in the fridge for two hours, or until set.
For the topping, place the milk chocolate pieces in a bowl set over a pan of hot water and leave until melted. Stir until smooth. Spoon into a piping bag fitted with a small plain nozzle and drizzle over top of the fridge cake. Leave to cool and chill for about 1 hour until set. Cut into squares and serve.