Place baking sheets in the oven and bake for 20-22 mn . Also take it out of the oven and let it cool completely.

Optional: Using a serrated knife to trim edges of puff pastry so it will fit in a 9-by-13-inch baking dish. Lay out a sheet of puff pastry

In a medium saucepan, whisk the milk, cream, butter, vanilla and sugar together over medium heat and cook until small bubbles appear around the edge of the pan, just before it comes to a boil. boiling.
Whisk the flour and water together to obtain a slurry, then stir the mixture into the hot milk mixture and remove the pan from the heat.

Whisk some of the hot milk mixture into beat egg yolks to soften the yolks, then while the pan is still off the heat, whisk the yolks into the batter until combined.
The pot is returned to the fire and left to boil. Whisking frequently, cook 30 to 60 seconds or until cream thickens.
Pour the thick custard over the puff pastry in a 9″ x 13″ baking dish, then cover with a second sheet of puff pastry. (Trim edges to fit dish) Press gently until dough sticks.

Placing baking dish in the refrigerator until cream hardens. 3-4 hours.
When ready to serve, sprinkling with powder sugar, slice & serve.

Enjoy!