01 -
Heat the milk and lemon zest in a saucepan over medium heat until simmering. Meanwhile, whisk together the granulated sugar, cornstarch, vanilla, whole egg, and egg yolk in a medium bowl until smooth. While whisking, pour the hot milk mixture into the sugar mixture; whisk until smooth, then pour the mixture back into the saucepan. Reduce the heat to medium-low and cook, whisking constantly, until the filling comes to a boil and is very thick, about 4 minutes. Add the white chocolate and stir until melted. Remove from heat and strain the filling through a fine-mesh sieve into a medium bowl, pressing it through with a rubber spatula. Press plastic wrap directly onto the surface and refrigerate until set and cold, at least 1 1/2 hours.
02 -
Beat 1 cup heavy cream and 2 tablespoons confectioners’ sugar with a mixer until stiff peaks form. Stir one-quarter of the whipped cream into the cold filling, then gently fold in the rest. Refrigerate the filling until set, at least 1 hour.
03 -
Combine the flour, eggs, milk, melted butter, granulated sugar, vanilla, and salt in a blender and blend until smooth, scraping down the sides. Add the food coloring and blend to combine. Let sit 1 hour.
04 -
Heat a 10-inch nonstick skillet over medium heat until hot. Lightly brush with butter, then pour in 1/4 cup batter; quickly tilt and swirl the pan to coat the bottom. Cook until the underside of the crêpe is dry and the top is firm, about 1 minute. Flip and cook until dry on the second side, 30 seconds (do not let the crêpes brown). Invert onto a parchment-lined baking sheet. Repeat to make about 15 crêpes, stacking them as you go and buttering the pan as needed.
05 -
Put 1 crêpe on a platter and spread to the edge with a scant 1/4 cup filling. Repeat with the remaining crêpes and filling, ending with a crêpe. Refrigerate the cake overnight.
06 -
Whisk together the remaining 3/4 cup heavy cream and 1 tablespoon confectioners’ sugar in a large bowl until soft peaks form. Spread on the cake. Top with nonpareils.