1

Preheat the oven to 180°C, fan 160°C, gas mark 4. Line a 12-hole muffin tin with paper cases.

2

Put the peas in a microwave-safe bowl, cover and cook for 3 minutes, until tender. Refresh under cold running water, then drain and transfer to a blender. Add the apple sauce, lemon zest and egg yolks and pulse until you have a smooth purée.

3

In a large bowl, whisk the egg whites using a hand-held electric whisk on medium speed until soft peaks form. Increase the speed to high and gradually whisk in the sugar until stiff, glossy peaks form.

4

Add the puréed pea mixture to the egg white mixture and gently fold until combined. Sift over the flour, baking powder and salt and gently fold until combined. Divide the mixture between the paper cases and bake for 15-20 minutes, until the cakes shrink away from the sides of the tin. Transfer to a wire rack to cool completely.

5

While the cakes cool, make the Swiss meringue. Put the egg whites, sugar and cream of tartar in a heatproof bowl and set over a pan of simmering water. Whisk constantly until the sugar is dissolved and the whites are warm to the touch; this will take about 2 minutes. Remove from the heat and continue to whisk using a hand-held electric whisk for 5-7 minutes until stiff, glossy peaks form (start on a low speed and gradually increase to high). Add the vanilla and salt and gently fold through the mixture.

6

Spoon the meringue into a piping bag fitted with a wide, plain nozzle and pipe onto the cupcakes.