Heat the oven and prep the tin. Set your oven to 160°C (140°C fan) and grease a 23x33cm rectangular baking dish or a 9x13 inch tin. Line the base with baking paper. The aroma of a warming oven is the first signal that your cosy project has begun.

Whisk the egg whites to stiff peaks. In a clean, dry bowl, beat the 6 egg whites with an electric mixer until they become foamy and opaque, like a cloud just before a storm. Gradually add half the sugar (100g), a spoonful at a time, and continue whisking until the peaks are stiff and glossy, and the bowl feels cool to the touch. Set aside.

Make the yolk mixture. In a separate large bowl, beat the 6 egg yolks with the remaining 100g of sugar until the mixture is thick, pale, and falls from the whisk in a thick ribbon. This should take about 3-4 minutes. Stir in the vanilla extract. The colour will shift from deep yellow to a buttery, almost white lemon shade.

Fold in the flour and whites. Sift the flour, baking powder, and salt over the yolk mixture. Gently fold in with a large metal spoon. Then, add a third of the whipped egg whites, folding until just combined. Add the remaining whites in two more batches, folding gently until no white streaks remain. The batter should be airy, pale, and look like a thick, soft mousse.

Bake until golden and springy. Pour the batter into the prepared tin and spread it evenly. Bake for 30-35 minutes. Your cue is a golden-brown top that springs back when lightly pressed in the centre, and a skewer inserted comes out clean. The kitchen will smell sweetly of toasted vanilla. Let the cake cool completely in the tin on a wire rack.

Prepare the three-milk soak. In a large jug, whisk together the sweetened condensed milk, evaporated milk, and 300ml of double cream until smooth. Once the cake is completely cool, pierce it all over with a fork or skewer. Pour the milk mixture slowly and evenly over the entire surface. You will hear a gentle, satisfying sizzle as the sponge begins to drink it in. Cover and refrigerate for at least 4 hours, or overnight. The cake will feel heavy and jiggly with liquid.

Whip the topping and serve. Just before serving, pour the chilled 600ml of double cream into a bowl with the icing sugar and vanilla. Whisk until soft peaks form. Spread the cream over the soaked cake, swirling it decoratively. Dust generously with ground cinnamon. The final cake should be a study in contrasts: a cloud of white cream over a deep, milk-soaked sponge.