• Preheat your air fryer to 160 degrees C, set it for 25 minutes, and prepare two cake tins that fit comfortably into your air fryer, greasing or lining if necessary.

For the Cakes:

• Whisk the margarine and caster sugar until smooth.
• Whisk in the eggs, one at a time.
• Add the lemon juice and zest, and mix well.
• Sift in the flour and baking powder.
• Whisk until smooth.
• Divide evenly between two cake tins.
• Place the first cake in the air fryer and bake for 15 minutes.
• After 15 minutes, open the air fryer and cover the cake tin carefully with foil or a suitable heatproof lid.
• Close the air fryer and cook for a further 10 minutes.
• Carefully remove the cover and use a skewer to make sure the cake is cooked. Return, covered, if necessary, checking every five minutes.
• Once the cake is cooked, remove it from the air fryer and leave it in the tin to cool.
• Repeat with the second cake.

For the Lemon Syrup:

• The first cake should still be warm when the second comes out of the air fryer. Leave both in the tins and stab all over with a wooden skewer.
• Place the caster sugar and lemon juice for the syrup in a small saucepan and warm over low heat for a few minutes, stirring often and taking care not to simmer, until the sugar has dissolved.
• Remove from the heat and pour liberally over the two cakes.
• Leave in the tins to cool completely.

For the Buttercream Filling:

• Once the cakes are cool, carefully remove them from the tins.
• Carefully level with a sharp knife or cake leveller if they have domed a lot.
• Soften the butter by beating it with a wooden spoon or whisking it carefully.
• Add the icing sugar and whisk or beat until the mixture is smooth.
• Add the lemon juice, tablespoon at a time, and whisk or stir until the mixture is even. Taste, and add more lemon for a stronger flavour or a more spreadable consistency.
• Pipe or spread onto the top of one of the cakes.
• Place the other cake gently on top.

For the Lemon Drizzle:

• Mix the icing sugar with a little lemon juice, adding a bit at a time until it’s a thick but pourable consistency.
• Pour roughly over the cake, or use a spoon to drizzle on.