In a large bowl, whisk together flour, sugar, and salt. In a separate bowl, whisk eggs, milk, melted butter, and vanilla. Gradually add wet ingredients to dry, whisking until just combined.

Cover the batter and refrigerate for at least 1 hour or overnight. This is a crucial step for tender crepes.

In a saucepan, heat 2 cups of milk and vanilla bean/extract until simmering. In a bowl, whisk together sugar, cornstarch, salt, and egg yolks until pale.

Slowly whisk half the hot milk into the egg yolk mixture. Pour it all back into the saucepan. Cook over medium heat, whisking constantly, until it thickens and boils for 1 minute. Remove from heat, whisk in butter. Strain through a sieve into a bowl.

Press plastic wrap directly onto the surface of the pastry cream and refrigerate for at least 4 hours, until completely cold and firm.

Heat an 8-inch non-stick skillet over medium-low heat. Pour ~3 tbsp of batter and swirl to coat the pan. Cook for 60-90 seconds per side, until lightly golden. Stack cooked crepes on a plate to cool completely.

In a separate bowl, whip the cold heavy cream to stiff peaks. Gently fold the whipped cream into the chilled pastry cream until smooth and combined.

Place one crepe on your serving platter. Spread about 1/3 cup of filling evenly over the crepe, leaving a small border. Top with another crepe. Repeat until you use all the crepes, ending with a plain crepe on top.

Cover the assembled cake with plastic wrap and refrigerate for at least 6 hours, or overnight, to allow the cake to set firmly.

Dust with powdered sugar and decorate with fresh berries, if desired. Slice with a sharp knife and serve chilled.