For the 1st layer: Preheat the oven to 180 degrees C (Gas 4). Mix biscuit crumbs with butter and press into the base of a 23cm (9 inch) cake tin (with a removable base) until it is even and firm.
Place the cake tin into the preheated oven and bake for 15 minutes.
Then cool and chill in the fridge for at least 3 hours.
For the 2nd layer: place all the 2nd layer ingredients into a non-stick saucepan and boil over low heat. When the marshmallows have melted, add in the gelatine (which must be dissolved in warm water first and stirred).
Scoop the mixture over the 1st layer. Chill again in the fridge for 3 hours, depending on the thickness of the layer. For best results, chill overnight.
For the 3rd layer: When the 2nd layer is ready, mix the jelly with hot water (refer to the packets instructions).
Cut the strawberries into half and place them on top of the 2nd layer.
When the jelly mixture has cooled (not to the extent that it has hardened), use a tablespoon to scoop the mixture up and form a thin layer to keep the strawberries firmly in their positions.
Place the cake tin into the fridge for 10-15 minutes. When time is up, continue scooping the mixture and then add layers of strawberries onto the cake until the strawberries are used up.
Chill until the jelly is firm. Cut into small pieces and place them in glass ramekins or cups.