Ingredients

• 350 ml strong espressofreshly brewed, or very strong moka; instant tastes thin against 500 g of mascarpone
• 2 tbsp coffee liqueuroptional
• 500 g mascarponefull-fat, out of the fridge twenty minutes so it whisks without lumps
• 300 ml double creamfridge-cold
• 80 g icing sugarsifted
• 1 tsp vanilla extract
• 250 g savoiardiItalian sponge fingers, dry and porous; soft ones collapse on contact
• 80 g dark chocolate70% cocoa, in a block
• 3 tbsp unsweetened cocoa powderfor dusting

Method

1. 01

   Cool the coffee completely

   Brew the espresso and pour it into a wide shallow dish. A pie dish is ideal, since you need to lay a whole sponge finger flat in it. Stir in the coffee liqueur if using and leave for 20-30 minutes until stone cold. Warm coffee dissolves savoiardi on contact and softens the cream; put the dish in the freezer for 10 minutes if you are in a hurry.

   350 ml strong espresso · 2 tbsp coffee liqueur

   If you cannot find savoiardiSliced stale sponge works, but press it into the coffee rather than dipping.

2. 02

   Loosen the mascarpone

   Put the mascarpone in a large bowl and beat it on its own with a spatula or low-speed whisk for 20 seconds, until smooth and creamy. Cold mascarpone whisked straight into cream goes lumpy, and those lumps never come out.

   500 g mascarpone

3. 03

   Whisk the cream layer

   Add the cold double cream, sifted icing sugar and 1 tsp vanilla to the mascarpone. Whisk on medium, not high, for 1-2 minutes, stopping to check every 20 seconds after the first minute. Stop as soon as it holds a soft, slumping peak and looks thick and glossy. Mascarpone contains a great deal of fat and goes from voluptuous to grainy and split in about ten seconds; if it does split, fold in two tablespoons of cold unwhipped cream by hand and it will usually come back.

   300 ml double cream · 80 g icing sugar

   For a darker versionReduce 100 ml of the espresso with two tablespoons of muscovado and add it back to the dip.

4. 04

   Dip the first layer

   Take a savoiardi and lay it flat in the coffee for one second on each side. Count it out loud. It should still feel firm in the middle when you lift it; it keeps absorbing on the way to the dish. Arrange a tight single layer in the base of a 20 x 28 cm dish, breaking fingers to fill the gaps. Over-dipped savoiardi are the single most common tiramisu failure and produce a wet, collapsing pudding.

5. 05

   Cream and chocolate

   Spread half the mascarpone cream over the savoiardi in an even layer, taking it to the corners. Grate about 40 g of the dark chocolate finely over the top on the small holes of a box grater, covering the surface completely.

   80 g dark chocolate

6. 06

   Repeat and chill

   Dip and lay a second layer of savoiardi, then spread over the remaining cream and smooth the top with a palette knife. Cover with cling film, not touching the surface, and chill for at least 6 hours and preferably overnight. This is not resting time. It is setting time: the savoiardi draw moisture from the cream and turn to sponge cake, and the whole thing firms into something you can serve in a piece.

7. 07

   Finish at the table

   Dust heavily with the cocoa through a small sieve just before serving. Dusted early, cocoa absorbs moisture and goes patchy and damp. Shave the remaining 40 g of chocolate into irregular curls with a vegetable peeler along the edge of the block and scatter them over. Serve with a large spoon, scooped rather than cut into neat squares; tiramisu is not meant to hold a sharp edge.

   80 g dark chocolate