Blueberry-lemon Tiramisu Recipe

Combine the blueberries, 75 g sugar, 30 ml water, 2 tablespoons lemon juice, and 1 teaspoon lemon zest in a medium saucepan over medium heat.

Bring to a gentle simmer, stirring occasionally so the sugar dissolves and the blueberries release juices, about 5–7 minutes.

Mix 1 teaspoon cornstarch with 1 tablespoon cold water to make a slurry. Stir the slurry into the simmering blueberries and continue cooking 1–2 minutes until slightly thickened.

Remove from heat and let cool to room temperature, then transfer to the refrigerator to chill while you prepare the mousse (compote will thicken further as it cools).

If using gelatin: sprinkle 1 teaspoon gelatin over 2 tablespoons cold water in a small bowl and let bloom 5 minutes. Warm gently (microwave 5–8 seconds or over a double boiler) until dissolved; do not boil.

In a large bowl, whisk 450 g mascarpone with 60 g powdered sugar, 2 teaspoons lemon zest, 2 tablespoons lemon juice, and 1 teaspoon vanilla extract until smooth and free of lumps. If using gelatin, whisk the dissolved gelatin into the mascarpone mixture until fully incorporated and slightly warm.

In a separate chilled bowl, whip 240 ml cold heavy cream to medium-stiff peaks.

Fold one-third of the whipped cream into the mascarpone mixture to loosen it, then gently fold in the remaining whipped cream until uniform and airy. Chill briefly if needed; the mousse should be pipeable but stable.

Make lemon syrup: combine 25 g sugar with 60 ml water in a small saucepan and warm until the sugar dissolves. Remove from heat and stir in 80 ml lemon juice (or adjust to taste). Let cool to room temperature.

Prepare base

If using a 9x9-inch (or similar) dish, line the bottom with sponge cake slices or ladyfingers. Lightly brush each piece with the lemon syrup — do not soak until soggy, just enough to moisten (about 1–2 teaspoons per piece). Reserve any leftover syrup for brushing the top later.

Spread half of the lemon mascarpone mousse evenly over the soaked sponge layer using an offset spatula. Smooth the surface to an even layer.

Spoon half of the chilled blueberry compote in an even layer over the mousse. Use the back of a spoon to spread, leaving small pockets of compote for texture.

Add a second layer of sponge cake or arrange remaining ladyfingers on top of the compote and brush lightly with remaining lemon syrup.

Spread the remaining lemon mascarpone mousse over the top layer of sponge, smoothing carefully. Finish with spoonfuls of the remaining blueberry compote on top, swirling gently into the mousse for a marbled effect if desired.

Cover the assembled tiramisu and chill at least 4 hours, preferably overnight, to allow flavors to meld and the mousse to set.

Before serving, garnish with fresh blueberries, remaining lemon zest, and optional mint leaves. If desired, dust very lightly with powdered sugar.