Lots of requests for this slice so here is the recipe:

Lemon Marshmallow Slice

For the Cake (make first)

3 eggs

1½ cups sugar

Finely grated rind one very large (or two medium) lemons

¼ cup lemon juice

1¼ cups cold water

3 cups self raising flour

125ml light olive oil (or other oil or melted butter)

Grease a slab tin 20cm x 30cm approximately (must be at least 3cm deep)

Line base with baking paper and grease over this.

Heat oven to 170 degrees C (fan forced).

Beat the eggs and sugar together until thick and creamy.

Add, all at once, the lemon juice and rind, water, self-raising flour and oil and fold together with a whisk until smooth.

Pour into the prepared tin, smooth out the top and bake for approximately 30 minutes or until a metal skewer inserted into the centre comes out clean. 

Leave to stand 5 minutes, then invert onto a wire rack.  Place another rack on top and invert.  Leave to cool.

For the lemon curd filling (make while the cake is baking)

4 teaspoons cornflour

Juice of 2 large lemons

Rind of 2 large lemons, finely grated

3 eggs, lightly whisked

1 cup sugar

125g butter, diced

Mix the cornflour with the lemon juice, then place with all the ingredients in a small saucepan.

Stir with a whisk over low heat until the mixture thickens.  Strain through a sieve.

Leave to cool (in the fridge is best), stirring occasionally.

For the marshmallow (make while cake is baking, cool, but only whip once the cake has been filled with the lemon curd)

250g sugar

15g gelatine

1¼  cups cold water

2 tablespoons lemon juice

In a 6 cup capacity saucepan, mix the sugar and gelatin together and then stir in the water.

Bring to the boil, stirring constantly, then reduce heat to medium low and simmer 12 minutes, stirring occasionally.

Remove from heat and cool, but not set.

(If it does, simply place the saucepan back over low heat until it melts again.)

When the marshmallow is needed, beat with an electric beater until thick and white and will hold its peaks.

Drizzle the lemon juice into the mixture, while still beating, until peaks form again (it will only take a minute or so).

To Assemble

Place the cake on a suitable platter.  Leaving a small edge around, cut strips or cubes to a depth of about 1cm.  Carefully slice off and remove with a small serrated knife.

Fill the cavity with the lemon curd and smooth out, like this:

Spread over the whipped marshmallow and leave to set (it only takes a few minutes).

To serve – cut into portions with a knife that has been dipped in hot water, then wiped dry.