Meringue Cake with Strawberries

Start with the whites. 300 g is roughly nine large eggs' worth — whisk them before the syrup goes anywhere near heat, because if the syrup overshoots and you're still cracking eggs, you've got burnt sugar and nothing to pour it into. The syrup goes to 121°C — this is not a guess-by-eye stage, get a thermometer, because under that the meringue stays soft and won't hold piped shapes, over it and the sugar starts to caramelise and you'll taste bitterness under the sweetness. No thermometer? Drop a bit into cold water — it should form a firm ball you can roll between fingers, not a thread that dissolves.

On an ordinary UK hob, this is the one place where you need to actually watch the pan rather than multitask — sugar syrup goes from "nearly there" to "too far" in under a minute once it passes 110°C. Pour it in a thin, steady stream down the side of the bowl, whisk running, not into the whisk itself or it'll spin sugar threads onto the bowl walls and never fully incorporate.

The oven stage is the one domestic kitchens get wrong most often, because 70°C with the door open sounds like nothing is happening. It is. A gap of a few centimetres (a folded tea towel wedged in the door works, or just let it sit ajar) lets steam escape instead of condensing back onto the meringue — that's what stops it turning sticky and soft on the outside after it looked perfectly dry an hour earlier. Four hours is the lower bound; the real test is a piece snapping clean and dry when you break it, not bending, not leaving tack on your finger.

The custard is a crème pâtissière, done properly: cornflour thickens it fast and holds it stable in the freezer without turning to ice-crystal slush, which plain egg-yolk custard would do. Cook it stirring constantly until it visibly thickens to coat the back of a spoon — don't walk away, egg yolks scramble silently and you won't notice until it's grainy. Cling film pressed directly onto the surface while it cools stops a skin forming, which otherwise you'd have to pick out or blend in, wasting the smoothness you just worked for.

Vanilla pod, not essence, because you want the actual seeds showing as flecks through pale custard — if you only have essence or paste, a teaspoon stirred in at the end does the job on flavour, you just lose the visual. Double cream is doing two separate jobs — whipped into the filling for lightness, and again for coating the sides — any cream with high enough fat to hold soft peaks when whipped will do, UK double cream (about 48% fat) is already the right one, don't substitute single cream, it won't whip at all.

Strawberries want to be ripe enough to give a little under your thumb, not rock-hard supermarket ones picked for shelf life — those have the acid but none of the sugar to balance the sweetness around them. Out of season, frozen and defrosted strawberries, drained well, will do for the inside layer where they're hidden in the filling; for the ones you can see, you do want fresh.

Patience is the actual ingredient list item nobody writes down: four hours drying, a long freezer set, a custard that needs to cool fully before you fold anything into it. Rush any of these and you don't get a different cake, you get a wet one.