Fill a large bowl with ice water and set aside.
Place yolks, sugar, cornstarch, milk, and salt in a medium saucepan and whisk until smooth and well combined. Cook over medium heat, whisking constantly until pastry cream begins to thicken, about 5 minutes. Once the mixture thickens, whisk until you see bubbles, then continue to cook and whisk for 1 minute or until an instant-read thermometer registers 180°F. Remove from heat and stir in butter and vanilla. Strain mixture through a fine-mesh sieve into a medium bowl. Set bowl onto ice bath to stop the cooking and prevent curdling. Cover the surface with plastic; refrigerate until well chilled, at least 2 hours or overnight.
Combine 6 tablespoons melted butter, milk, eggs, vanilla, flour, sugar and salt in a blender. Blend on high speed until smooth and well combined, about 30 seconds. Refrigerate batter at least 1 hour.
Heat an 8-inch nonstick pan over medium heat. Use a pastry brush or paper towel to coat the pan with a thin layer of remaining melted butter. Ladle in a scant 1/4 cup of batter and quickly swirl the pan to cover the bottom with a thin layer of batter. Cook for about 1 minute, or until the edges are golden brown. Run a rubber spatula around the edge to loosen, then carefully flip the crêpe. Cook another 20- 30 seconds, or until the bottom is browned in spots. Transfer to a plate to cool.
Repeat until all of the batter has been used, buttering the pan each time. You should have about 27 crêpes (you’ll need 25). Cover loosely and let crêpes cool to room temperature.
To assemble cake, place one crêpe on the center of your serving plate. Spread 2 tablespoons of pastry cream evenly on top. Repeat layering crêpes and filling. Top with final crêpe and refrigerate for at least 4 hours and up to 1 day.
When ready to serve, make the ganache. Combine chopped chocolate and corn syrup in a medium bowl. Heat heavy cream in a small saucepan until bubbles just begin to form around the edges. Pour cream over chocolate and let sit for 2- 3 minutes. Whisk until smooth and shiny. Pour ganache over the top of the crêpe cake.
Top with whipped cream and chocolate curls and enjoy.