Mocha chip icebox cake

Dab butter on a round of parchment and press it into the bottom of a 9-inch springform pan.

Combine white sugar, instant coffee or espresso powder, a little unsweetened cocoa, a splash of vanilla extract and coffee liqueur, then add two cups of very cold heavy cream.

Whip until it just starts to thicken, like a thin pancake batter, then add the mascarpone.

Continue whipping to fairly stiff but not too stiff peaks; stop before the cream or mascarpone over-mixes and separates. A spoon dragged through should leave a sharp line.

Lay a layer of crisp cookies in the pan, whole ones first and broken pieces in the gaps, and spread exactly a quarter of the mocha filling over them.

Repeat to five layers of cookies and four of filling, pressing the cookies down as the layers build.

Wrap in plastic, press down once more and chill at least 12 hours, best 24.

Run a thin knife dipped in hot water around the edge and remove the ring; smooth with a knife or spatula.

Optionally pipe plain whipped cream on top with a star tip and dust with cocoa.