Sponge method:
Heat oven to 190c. Line a sponge tin with baking paper and spray lightly with baking spray.

Add the egg whites and cream of tartar to the clean, dry bowl of a stand mixer and beat with a whisk attachment on low speed for a few minutes until the whites are foamy.

Turn the speed up and continue to beat, adding in half the sugar (⅓ cup) slowly a teaspoon at a time, allowing it to dissolve before adding more. Keep beating until stiff peaks form and the mixture is smooth, thick and glossy.

While the egg whites are beating, mash the avocado well in a large bowl until it’s completely smooth. Blend the pistachios in a food processor until fine. Add the remaining sugar, vanilla and ground pistachios to the avocado and combine.

Add the flour, baking powder and salt to the avocado, and stir through until smooth. Now add a third of the egg whites to the avocado mix and carefully fold through with a spatula until combined, being careful to go slowly and knock as little air out of the whites as possible. Continue with another third until combined, then the last. The mix will be light and fluffy.

Spread it all out onto the prepared baking sheet, level it out and bake for 13-15 minutes, or until you can lightly press down on the sponge with your finger and the cake springs back. Be careful not to overbake.

When the sponge is just done remove it from the oven and immediately turn it out onto a clean dry tea towel dusted with icing sugar. Remove the baking paper and carefully roll the cake up (from short end to short end), so that the tea towel is rolled up inside too. This ensures the cake won’t stick to itself as it cools. With your cake now fully rolled up into a log, gently place it on a wire rack and leave it to cool completely inside the tea towel.

Cream filling:
When the sponge is cool, beat the cold cream, vanilla paste and icing sugar in a stand mixer with a whisk attachment for a few minutes until thick and billowy. It should be just thick enough to spread out and hold it’s shape. Gently fold through the chopped strawberries.

To assemble:
Carefully unroll the sponge, and top it with roughly ⅔ of the cream filling and spread it out evenly leaving 2cm of space round the edges. Now it’s filled, roll it back up lightly making sure the cream doesn’t get pushed out the sides. Transfer the roll to a serving plate, then top with the rest of the cream using a piping bag. Decorate with more fresh strawberries, icing sugar and pistachios if you like, and serve. Best eaten on the day it’s made.

Recipe created for The Avo Tree by Semla Studio