In a medium bowl, stir together 1/3 cup milk with flour, salt and whisk until smooth. Add the yolks and 3 tbsp. sugar and whisk vigorously until mixture is smooth and pale lemon in color.
In a heavy bottom saucepan, heat remaining milk with the remaining 3 tbsp. sugar and vanilla scraping over medium heat. Heat until milk just comes to a boil. While stirring the yolk mixture, slowly pour ¼ of the hot milk into the yolk mixture. This will temper the egg yolks so they don’t start to scramble. Immediately pour yolk mixture into hot milk in the saucepan. Whisk over medium heat until mixture comes to a boil and thickens.
Remove from heat immediately. Cover with plastic wrap to prevent skin from forming. Cool completely.
Cut the Plein Soleil Puff Pastry into very thin rectangles.
Preheat oven to 220°C.
Line a baking sheet with parchment paper. Lay dough on top and poke with fork all over to prevent over rising.
Bake until golden brown and very crisp. Cool completely on rack.
Trim pastry so edges of rectangle are straight and even in shape. Divide the rectangle into 2 or 3 even strips.
Evenly divide cooled pastry cream onto two strips of puff pastry. Spread evenly.
Cover the base with cream & Plein Soleil Mixed Berries. Lay one strip on top of it & cover it also with cream & Mixed Berries. Top with final strip of puff pastry. Dust with icing sugar. Chill for 1 hour before serving.