Step 1

Prepare the custard first to allow for cooling time. In a large mixing bowl, whisk together the egg yolks and sugar for a minute. In a separate ramekin, combine the cornstarch and water to form a slurry. Add the cornstarch slurry to the egg yolk mixture. Whisk the mixture vigorously for 2 to 3 minutes, until it's pale in color and ribbons off of the whisk.

Step 2

Into a separate saucepan, add the milk and flour. Heat the milk over medium heat, whisking constantly, until the milk is steaming hot but not boiling. Slowly temper the hot milk into the egg yolk mixture - add a little bit at a time and whisk well after each addition until all the milk is added.

Step 3

Pour the mixture back into the sauce pan. Cook it over medium heat, stirring constantly with a rubber spatula, for 4 to 5 minutes. The mixture will thicken and take on a pudding-like consistency. Remove it from heat and add the butter. Whisk in the butter until it's completely melted. Cover the custard with plastic wrap touching the surface and place into the refrigerator to chill.

Step 4

TIP: to cool the custard down quickly, spread it in a thinner layer over a larger baking dish.

Step 5

Once the custard is cooled, finish preparing the filling. Add the softened mascarpone cheese and whisk until the cheese is well incorporated into the custard. Pour in the chilled heavy cream and whisk the mixture on high speed for 4 to 5 minutes until the mixture is fluffy and forms soft peaks.

Step 6

For the strawberry puree, place the strawberries and sugar into a food processor or blender and pulse into a fine puree.

Step 7

To assemble the cake, use a 9-inch spring form pan. Create the outer ring of ladyfingers first - dip the cookies into the puree on one side only, then place around the edge of the pan. Create the first layer of the cake the same way. Cut the cookies into smaller pieces if needed to fit. Top the first layer of ladyfingers with a generous amount of custard filling.

Step 8

For the remaining layers, dip the cookies all the way into the puree for a second. Add alternating layers of cookies and custard filling. Top the cake with a layer of custard.

Step 9

Place the cake into the refrigerator and chill overnight, or for at least 8 hours. When ready to serve, use a cake lifter or large spatulas to transfer the cake onto a stand. Tie a ribbon around the cake for presentation. Garnish the top with sliced strawberries when ready to serve.