Step 1

Put all of the ingredients in a saucepan and cook it over medium-low heat whisking constantly.

Step 2

Once the butter melts, the consistency of the mixture will be thin, don't increase the heat. Keep whisking until the mixture thickens for about 5 minutes.

Step 3

When the mixture thickens, transfer it to a fine-mesh strainer set over and bowl and strain the mixture from any unnecessary lumps. This will give you a perfect and smooth curd.

Step 4

Cover the bowl tightly with plastic wrap and let the mixture cool for about 20-30 minutes.

Step 5

In a large mixing bowl, add the heavy cream, vanilla extract, lemon zest, lemon curd, lemon juice, and sugar, and mix with an electric hand mixer until well combined and medium peaks are formed.

Step 6

Add the mascarpone cheese and cream it on low speed until the mixture is smooth.

Step 7

Dip the ladyfingers quickly in the lemon syrup and lay them in an even layer in the 10.5-inch x 7.5-inch baking pan.

Step 8

Top the soaked ladyfingers with half of the mascarpone mixture and smooth it out with a spatula.

Step 9

Spoon 4 tbsp of lemon curd on top and smooth it out with a spoon.

Step 10

Add another layer of the dipped ladyfingers and top it with the remaining mascarpone mixture. Smooth it out with an offset spatula.

Step 11

Cover the pan tightly with plastic wrap and refrigerate for at least 4 hours.

Step 12

Top the tiramisu with lemon curd and smooth it out with a spatula.