In a large mixing bowl with the paddle attachment, add the flour, salt, sugar, and butter and mix until bread crumb consistency. You can also use a food processor and pulse a few seconds. By hand just rub the butter into the flour mix using your fingers until crumbs are achieved.

Add in the eggs and mix or pulse just until a dough is formed. If mixing by hand, work in the eggs into the flour mixture using your fingers until the dough starts to develop.

Transfer the tart pastry dough onto a light flour work surface and form it into a ball. Slightly flatten the pastry dough and refrigerate for at least 1 hour.

Remove the dough from the refrigerator and transfer onto a lightly dusted work surface.

Roll out the dough using a rolling pin, dusting the top with flour to prevent the dough from sticking to about 4mm thickness.

Use a 2 1/2 or 3 inch round cookie cutter to cut out the dough discs.

Poke the bottom of the pastry dough in the tart cup and bake at 356°F or 180°C and bake for 10-12 minutes until golden light brown.

Cool with pastry shell in the tart mold and set aside.

In a large pot on medium heat, add the mascarpone, parmesan, cream cheese, mascarpone cheese, parmesan cheese, salt, butter, and milk and cook stirring constantly until mixture is melted and well combined.

Add in the cornstarch and icing sugar and continue to cook on medium heat stirring until the mixture thickens.

Reduce the heat to low and add in the vanilla extract and lemon juice and mix to combine, the mixture will be thicker.

Add in the eggs and mix until well blended and remove from heat.

Fill each tart shell just under the rim of that tart shell with the custard cheese filling and brush the top with some egg yolk.

Repeat until all the tart shells are filled.

Place into oven and bake at 430°F or 220°C for about 5-6 minutes or until the tops are light golden brown.

Remove from the oven and cool.

Serve and enjoy.