Directions

1. Place bowl and spatula in the fridge prior to using. Mix together the flour and salt in your bowl. Grate your butter on top of the flour mixture, working quickly. Mix all together until the mixture turns coarse and crumbly. Add 6 tablespoons ice water one tablespoon at a time and mix with a spatula before adding the next one until the dough comes together. Add another tablespoon of ice water if you see there is an excess of flour in the bowl and the dough is dry.
   
2. Use your hands to press the dough together into a ball and quickly form a rough disk. Immediately wrap your rough puff pastry dough in plastic wrap and chill it in the refrigerator for at least 30 minutes/freezer for 15 minutes.
   
3. Flour a surface and your rolling pin thoroughly. Transfer dough to a floured surface and use rolling pin to roll it out into a 6x15 inch rectangle. Use the rolling pin to push the edges of the dough inward if they begin to crack; keep your rectangle’s edges straight. Work quickly to keep the dough cool. Fold one side of the dough over the top of the middle third of the dough and fold the remaining third of the dough on top of that. Brush off excess flour from the dough, re-wrap the pastry in plastic wrap, and chill in the refrigerator for at least 30 minutes/15 minutes in freezer.
   
4. Roll the dough out again into a 6x15 inch rectangle. Fold one side of the dough over the top of the middle third of the dough and fold the remaining third of the dough on top of that. Rotate the dough 90 degrees and repeat the same process, rolling out the dough into 6x15 inch rectangle and folding the pastry into thirds. Brush off any flour, wrap the pastry again in plastic, and chill in the refrigerator for another 30 minutes/15 minutes for freezer.
   
5. Repeat the same steps you performed in the last turn. Wrap and return to the refrigerator. The pastry can be used after 90 minutes.
   
6. Roll out the puff pastry into a 10x12 inch rectangle. From the 10-inch side, start rolling the pastry into a tight roll until you have a 10-inch long roll. Return the pastry to the freezer for 30 minutes to chill until firm.
   
7. Cut the pastry roll into 12 equal disks, cut the pastry in half twice, and then cut each of the remaining 4 pieces into 3 equal pieces. Start with 6 pieces, wrap the rest up, and put them back in the refrigerator.
   
8. On a lightly floured surface, place each piece of dough so the swirls face up. Use a rolling pin to roll each piece into a flat disc about ¼ inch wider than the diameter of the tin. Place each disk onto the bottom of each tart tin and press the dough onto the tin. When you spread the dough into the tart tin, form a lip that sits on top of the perimeter of the tin. Work quickly so your dough doesn’t heat up. Have some flour on the side in case the dough sticks try not to overwork it. Freeze the tart cups for at least 35 minutes or until frozen. You can make the pastry tins ahead of time and keep them frozen for up to 2 weeks.
   
9. Whisk heavy cream, sugar, milk, egg yolks, cornstarch, and vanilla extract in a small saucepan until the sugar is dissolved. Place over medium low heat, continuing to whisk until the mixture begins to coat the sides of the pan. The custard should get just hot enough so you see steam beginning to form. This is your signal that the custard is almost ready. When the custard is thick enough to coat a spoon, remove from the heat and continue to whisk, ensuring you scrape the sides of the pan. Whisk until it is no longer hot. It’s a fairly thin consistency. Set aside to cool completely, pressing plastic wrap onto the surface of the custard so a skin does not form on top.
   
10. Preheat the oven to 475 degrees F. Place the pastry shells on a sheet pan, lined with parchment. Spoon the custard in each shell until the custard is right below the top lip of the mold, work quickly.
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11. Put the pan on the middle rack of your oven, and immediately turn the oven temperature to 450 degrees. Bake for 15 minutes then rotate and bake for another 15 minutes. Remove the custard tarts from the oven and place on a rack to cool.