Preheat the oven to 180°C, gas mark 4. Grease and line a 1.5-litre loaf tin.
Put the butter and 180g caster sugar in a bowl. Beat with an electric hand whisk until pale and fluffy.
One at a time, beat in the eggs. Stir in the flour, ground almonds, baking powder, 2 tbsp lemon curd and lemon zest.
Spoon the batter into the prepared tin and level the surface with a spoon. Bake for 40-45 minutes, covering with foil after 25 minutes, until a skewer inserted into the centre comes out clean.
Combine the lemon juice and 100g caster sugar. Use a skewer to pierce holes right through the warm loaf then spoon the drizzle over the top. Leave to cool in the tin.
When the loaf is completely cold, carefully slice horizontally into 3 even layers.
Place the bottom loaf layer crust-side down on a cake stand or plate and spread with 2 tbsp lemon curd. Place the middle layer on top then spread with the remaining 2 tbsp lemon curd. Top with the final layer.
Put the 2 egg whites, remaining 50g caster sugar, the icing sugar and the cornflour in a large heatproof bowl.
Beat with an electric hand whisk until combined then set over a pan of barely simmering water.
Continue to whisk for 5-7 minutes, or until the meringue is very thick and holds its shape.
Spread the meringue over the loaf. Use a blowtorch to lightly brown before you serve.