Preheat the oven to 180 °C (355 °F). Line the bottom and sides of a 24 cm (9.5 inch) loose bottom cake tin with parchment paper.
Blend the crackers with the butter, then press the crumbs into the bottom of the cake tin. Bake for approximately 10 minutes, or until golden brown around the edges.
In a large bowl mix the cream cheese with the yogurt.
Soak the gelatin in a little cold water.
Mix together the cooking cream, sugar, the juice and zest of half a lime, in a pan over a low heat until the sugar is completely dissolved. Remove from the heat.
Drain the water from the gelatin, and gradually add the gelatin to the pan, mixing until dissolved.
Gradually pour the mixture over the cream cheese and yogurt and stir until smooth.
Put one third of the cream mixture in the tin over the cracker crust, then add the sliced bananas and the blueberries. Pour over the remaining cream and refrigerate for at least 5 hours.