01 -
Set your oven to 400°F. Lay out two baking trays with parchment paper. Grab the pastry sheets and poke them all over with a fork so they don’t puff up too much. Slide them in the oven and bake for about 12 or 15 minutes until they look brown and crunchy. Wait for them to cool. Cut one sheet so it lays flat in the bottom of an 8×8-inch dish. Keep the second piece aside for later.
02 -
Drop your sugar, cornstarch, and salt into a saucepan. Whisk in the yolks. Slowly pour in milk and cream as you whisk, so everything gets smooth. Put the pot on medium. Keep stirring till it thickens and gently bubbles—about 7 to 10 minutes. Pull off the heat. Mix in butter and vanilla until it’s shiny. Let this cool down, giving it a stir now and then so it doesn’t form a skin, for about 5 or 10 minutes.
03 -
Line the baking dish with one cool pastry sheet. Pour in the warm custard and spread so it’s even. Set the second pastry on top, press lightly so it sticks. Put the whole thing in the fridge and leave it alone for at least 4 hours, or even overnight, until everything firms up.
04 -
When you’re ready to eat, shake a little powdered sugar on top. Cut it into squares using a sharp knife, wiping the blade each time so you get tidy pieces. Tastes best cold.