Berry Gateau

For the cake: heat the oven to 170°C (150° fan) 325°F gas 3. Line the base of a deep 20cm|8" springform tin with non-stick baking paper.

Stir together the flour, xanthan gum and baking powder in a mixing bowl. Add all but 3 tablespoons of sugar and all the salt. Stir to combine.

Whisk together the oil, egg yolks, water, vanilla and lemon zest.

Add to the dry ingredients and mix well until very smooth.

Whisk the egg whites until frothy. Add the cream of tartar and whisk until softly peaking.

Slowly add the remaining sugar and whisk until firm and glossy.

Gently fold in about 1/3 of the whites into the yolk mixture, then gently fold in the remaining whites until just combined.

Pour into the tin and bake for 45-55 minutes until a skewer inserted into the centre comes out clean. Cool in the tin on a wire rack.

For the lemon syrup: put the lemon juice, sugar and water into a small pan. Heat gently and then boil for 2 minutes. Allow to cool completely.

For the filling: pour the milk, vanilla and salt into a heavy-based pan. Heat to almost boiling, stirring occasionally.

Mix together the cornflour and sugar. Add the egg and whisk until smooth.

Pour the heated milk in a thin stream into the egg mixture, whisking constantly.

Pour the mixture back into the pan and cook, stirring until thick enough to coat the back of a spoon.

Remove from the heat and pour through a sieve into a large bowl. Allow to cool for 10 minutes, stirring occasionally.

Cut the butter into small pieces and whisk into the pastry cream a piece at a time, until smooth.

Cover the pastry cream with cling film directly on top of the cream to prevent a skin from forming. Chill in the refrigerator.

In a small bowl, sprinkle the gelatine over the water and stand for a few minutes to soften.

Measure 60ml|1/4 cup of the chilled pastry cream into a small heatproof bowl over a pan of simmering (not boiling) water. Heat the cream to 49°|120°F

Add the gelatine and whisk until smooth. Remove from the heat and gradually whisk in the remaining chilled pastry cream.

Whisk the cream until thick, then immediately fold into the pastry cream.

Remove the cake from the tin. Line the tin with cling film. Slice the sponge in half horizontally and place one half in the tin, cut side up.

Brush evenly with some of the lemon syrup.

Slice in half enough strawberries to arrange around the sides of the cake tin Place the cut side of the strawberries against the sides of the tin, point side up forming a ring.

Spread some of the pastry cream in between the strawberries and a thin layer across the top of the cake.

Chop the remaining strawberries and place them in the middle of the cake. Cover the strawberries entirely with the pastry cream.

Place the second cake layer on top and brush with lemon syrup.

Chill for at least 4 hours until the filling has set.