1-First Step: Get everything ready Start by zesting and juicing the lemons, then set everything aside so the process flows smoothly. This dessert moves quickly once the curd and syrup begin cooking, so having all ingredients measured and ready will make things easier. If you are using limoncello, keep it nearby, but do not add it until the syrup is fully cooled.

2-Second Step: Cook the lemon curd In a heat-proof bowl, whisk together 4 large egg yolks, 2/3 cup granulated sugar, 1 tablespoon lemon zest, 1/3 cup fresh-squeezed lemon juice, and a pinch of salt. Place the bowl over simmering water, making sure the bottom does not touch the water. Stir constantly for 7 to 10 minutes until the mixture thickens to a gravy-like consistency. The lemon curd should coat the back of a spoon. If you draw a clean line through it with your finger, the line should stay in place. If it is still runny, keep cooking it a bit longer. This step is important because the curd gives lemon tiramisu its bold citrus layer.

3-Third Step: Finish and cool the curd Once the curd thickens, remove it from the heat and stir in 6 tablespoons of room temperature butter, chopped into pieces. Stir until smooth and glossy. If you want a very silky texture, you can strain the curd through a fine sieve. Place plastic wrap directly on the surface of the curd to stop a skin from forming, then refrigerate it until fully cool. A chilled curd spreads better and keeps the layers neat when you assemble the dessert.

4-Fourth Step: Make the lemon syrup In a saucepan, combine 3/4 cup fresh-squeezed lemon juice, 1 cup water, and 1/2 cup sugar. Bring the mixture to a boil and cook for about 5 minutes until the sugar dissolves fully. Remove from heat and cool it completely before using. If you want to add limoncello, stir in 1/4 cup after the syrup has cooled. Adding it too early can cook off the flavor, so waiting is the best move. The syrup should taste bright, sweet, and tart enough to soak into the ladyfingers without making them soggy.

5-Fifth Step: Whip the mascarpone filling In a mixing bowl, beat 8 ounces of room temperature mascarpone with 1 tablespoon lemon zest until smooth. Then pour in 1 1/2 cups heavy whipping cream and whip just until medium to stiff peaks form. Stop as soon as the mixture is fluffy and stable. Do not overmix, since mascarpone can turn grainy if it is beaten too long. If you want an even smoother texture, chill the bowl and beaters before starting. The filling should be thick enough to hold its shape while still looking soft and creamy.

6-Sixth Step: Assemble the lemon tiramisu Use an 8×8-inch pan for the best layering. Quickly dip each ladyfinger into the cooled lemon syrup, turning it just enough to soak the outside without letting it fall apart. Line the bottom of the pan with the dipped cookies. Spread half of the mascarpone mixture over the ladyfingers. Then add a layer of cooled lemon curd. Repeat the layers with the remaining ladyfingers, the rest of the mascarpone, and any extra curd if you have some left. Finish with the remaining mascarpone layer on top.

7-Final Step: Chill and garnish Cover the pan and refrigerate the lemon tiramisu for at least 2 hours, or overnight if you have time. The chilling time lets the flavors blend and helps the dessert set for clean slices. Right before serving, add grated white chocolate, lemon zest, or thin lemon slices if you want a pretty finish.