For the base:

1 Preheat the oven to 200 degrees or 180 if using a fan oven. Line a 20x20cm high-sided square tin with parchment paper, ensuring the paper comes up and over the sides of the tin. This will make the traybake easy to remove from the tin once baked. If you don't have a square tin, you can bake this dish in a 20cm round springform cake tin.

2 Blend the ginger biscuits in a food processor or smash up in a sealed bag to a fine crumb. Pour the crumbs into a bowl, add the salt and melted butter, and mix well to combine. Press the crumb into the prepared tin using your hand or the back of a spoon, ensuring it is well compacted.

3 Bake the base in the preheated oven for 10 minutes. Remove the base from the oven and let it cool slightly while you make the filling.

For the filling:

1 Reduce the oven temperature to 180 degrees or 160 degrees if using a fan oven.

2 Whisk the egg yolks, lime zest, lime juice, lemon juice, condensed milk, cream, and icing sugar together in a large bowl until smooth and well mixed. Pour the mix into the cooled baked base and return to the oven for a further 40 minutes, until the edges are just set but the centre still has a slight wobble. If the edges have not yet set, bake for a further five minutes and check again.

3 Remove the traybake from the oven and leave to cool completely in the tin, for at least an hour. Chill the traybake in the tin for at least three hours before cutting. At this stage you can also freeze it, to cut and serve another time. Once set, cut the traybake into squares, or wedges if using a round tin, and serve with the lime cream topping.

For the topping:

1 Whisk the cream with the lime zest and icing sugar until you reach soft peaks and serve spoonfuls of the lime cream on top of the lime squares.