Whip the cream. Pour the double cream into a large, chilled bowl. Add the caster sugar and vanilla extract. Using an electric hand whisk or a balloon whisk (if you fancy an arm workout), whip until the cream holds stiff peaks. You'll know it's ready when you lift the whisk and the cream stands up in firm, glossy points without drooping. The mixture should look thick and smooth, almost like a cloud.

Prepare your dish. Choose a 20cm x 20cm square baking dish or a similar-sized rectangular one. Spread a thin layer of the whipped cream across the bottom — just enough to stop the biscuits sliding around. You'll hear a soft squelch as you spread it.

Layer the biscuits. Arrange a single layer of digestive biscuits over the cream. They should fit snugly, but it's fine if you need to break a biscuit in half to fill gaps. Press them down gently so they stick.

Add strawberries and cream. Spread a generous layer of whipped cream over the biscuits — about one-third of what's left. Then arrange a layer of sliced strawberries on top. The berries should overlap slightly, creating a pretty pink-and-red patchwork. You'll see the cream turning pale pink at the edges as the strawberry juices start to mingle.

Repeat the layers. Add another layer of biscuits, pressing them gently into the cream. Then another layer of cream and strawberries. Continue until you've used all your ingredients, finishing with a thick layer of cream on top. The final layer should be smooth and even; use a spatula to swirl it into soft peaks if you like a decorative finish.

Chill overnight. Cover the dish tightly with cling film and refrigerate for at least 6 hours, but overnight is truly best. During this time, the biscuits will absorb moisture from the cream and strawberries, transforming from crunchy to soft and cake-like. The texture should be tender but not mushy — you want the biscuits to hold their shape when you cut a slice.

Finish and serve. Just before serving, dust the top with icing sugar through a fine sieve. Add fresh mint leaves if you like. Cut into squares and watch the layers hold together beautifully. The sound of the knife slicing through the soft cream and tender biscuits is deeply satisfying.