• Preheat the oven to 180°C / 350°F and grease and line a 28x35cm / 9 x 13 inch cake tin with baking paper. Allow 2 sides of the baking paper to be longer and stick up as tabs to help remove cake when baked.
• In a medium bowl, sift in the flour, cornflour/starch, and baking powder 2-3 times to ensure no lumps and the baking powder is fully distributed through the flours.
• In another large mixing bowl, beat the eggs and egg yolk together using a hand mixer until frothy. Gradually add the white sugar while continuing to beat the mixture until ribbon stage and becomes thick and pale. It should be thick enough that you can do a figure-8 motion and it stays on the surface for 3-4 seconds.
• Sift the plain flour, cornflour/starch, and baking powder into the egg mixture. Fold gently with a balloon whisk and let gravity move the mixture through the whisk. Use slow movements. Over-mixing can cause the batter to deflate, resulting in a dense cake.
• Add in the melted butter and vanilla extract, and fold until just incorporated. Ensure you fold from the bottom of the bowl and butter can pool there.
• From a low height, pour the batter into the cake tin, this helps prevent deflating the batter. Smooth the surface with a spatula.
• Bake for 12-16 minutes, or until lightly golden and when a toothpick is inserted into the centre of the cake, it comes out mostly clean.
• While the cake is baking, prepare a clean, dry tea towel. Generously dust half of the extra cornflour/starch over the tea towel. This is to help prevent it from sticking and to create a smooth surface. Avoid powdered sugar as it may make the cake surface moist.
• Remove the cake from the oven and let it cool for ONLY 1-2 minutes in the pan before running a sharp knife along the sides of the cake to loosen it. Gently lift the cake from the tin. In one quick motion, carefully flip the cake onto the prepared tea towel. Gently remove the baking paper.
• Sift over the remaining cornflour/starch on top of the cake. Starting with the short side, gently roll up the cake keeping the tea towel wrapped around the cake. Cover cake roll in clig wrap and place in the fridge for 30 minutes and allow the cake to get cool (but not cold) rolled up.

Make the Vanilla Whipped Cream

• Meanwhile, prepare the vanilla whipped cream by combining the heavy whipping cream, powdered icing sugar, and vanilla extract in a mixing bowl. Beat the mixture until stiff peaks form.

Bring It All Together

• Once the cake has cooled, gently unroll the cake, allowing it to stay slightly curled. Spread generously with jam and vanilla whipped cream and sliced strawberries. Carefully roll the cake back up.
• Place cake back in the fridge for at least 1 hour before dusting with powdered icing sugar and serving slices.