Take a 20x20cm trifle bowl. I used this one from Amazon.
Cut the swiss roll up into 16 slices at about an inch each slice. Place the swiss roll around the edge of the bowl at the bottom and in the middle. This should use up about 10 of them. Keep the rest for later.
Cut each creme egg in half. See above for the best method.
Place a half in between each swiss roll, resting on the join where they meet.
For the mousse put the marshmallows, butter, chocolate and water into a saucepan and melt on a low heat. Stir every now and then until it has melted.
Whip your double cream until thick but still spreadable. Fold it in to your cooling chocolate mixture until everything is combined. You should have a nice, smooth mixture.
Pour the mousse mixture into the bowl and then place it into the fridge for about 5 hours or until set. I like to leave mine in overnight if I have the time.
Repeat another layer of creme egg halves in between the others. Push into the mousse slightly to help support them. With your left over swiss roll break up into small chunks and fill another layer.
To finish whip the double cream up until think but still spreadable. Retain 3 tbsp of cream to whip for decoration. Spoon in a thick layer of cream on top of the trifle and smooth over.
Whip the remaining cream until it is a bit thicker and put 6 blobs around the top. Unwrap each lint bunny and push into each blob of cream. Grate some dark chocolate to finish.