There's a particular smell that fills the kitchen when butter and brown sugar and condensed milk start to come together over a low heat. Toffee, but warmer. Toast, but sweeter. The kind of smell that makes whoever else is in the house drift toward the kitchen without quite knowing why. This is a recipe to make on a wet afternoon when you've nowhere to be and an hour or two to spend properly.

Millionaire's shortbread is three things stacked on top of each other and pretending to be one. A buttery shortbread base. A thick layer of caramel cooked patiently from a tin of condensed milk. A snap of dark chocolate over the top. None of it is complicated. All of it asks for a bit of attention. We're only making dinner, except this isn't dinner, it's the thing you take to a friend's house in a tin and watch disappear before the kettle has boiled.

The trick, if there is one, is patience with the caramel. You stand over the pan and stir, and stir, and then stir some more, and just when you start to suspect nothing is happening, it changes. The colour deepens. The texture thickens. It pulls away from the bottom of the pan in slow, glossy folds. That's the moment. Take it off the heat.

I made a tin of these last week to take somewhere and there were none left to bring home. I wrote it down in the notebook: shortbread, caramel, chocolate, gone. There are few better feelings than putting a tin like this in front of people and watching it empty.