Line an 8x8-inch tin with baking paper and set aside. This will make it easier to lift the fudge out once it's set.
Add the milk chocolate, condensed milk and the Kinder chocolate bars to a heatproof bowl. Gently heat in a double boiler (or in 20-second bursts in the microwave) until the chocolate has melted and the mixture is thick.
Mix the Kinder Bueno bars into the fudge mixture then transfer it into your lined tin. Press it into place using a rubber spatula or back of a spoon.
Topping
Top the fudge with the rest of the Kinder chocolate and Kinder Bueno pieces.
Refrigerate for 1-2 hours until firm, then cut into squares and enjoy.
Video
Notes
Store in an airtight container at room temperature for up to 1 week.