Make the filling: Whisk the egg yolks, granulated sugar, cornstarch, orange zest, orange juice, lemon juice and salt in a medium saucepan. Cook over medium heat, stirring constantly with a rubber spatula until the mixture comes to a simmer and is thick like pudding, 10 to 12 minutes. Remove from the heat and stir in the butter until melted. Strain the filling through a fine-mesh sieve into a large bowl, pushing it through with a rubber spatula. Press plastic wrap onto the surface of the filling and refrigerate until cold and firm, at least 2 hours.
Meanwhile, make the crepe batter: Combine the flour, eggs, milk, melted butter, granulated sugar, vanilla and salt in a blender; blend until smooth, scraping down the sides of the blender as needed. Set aside, covered, 1 hour. (This prevents the crepes from turning out rubbery.)
Finish the filling: Beat the heavy cream in a large bowl with a mixer on medium-high speed until it starts thickening, about 1 minute. Add the confectioners' sugar and beat until stiff peaks form, about 1 more minute. Beat in the vanilla. Stir one-quarter of the whipped cream into the orange filling, then gently fold in the rest. Cover and refrigerate until set, about 1 hour.
Make the crepes: Line a baking sheet with parchment paper. Heat a 10-inch nonstick skillet over medium heat. Lightly brush with butter, then pour 1/4 cup batter into the center of the pan. Quickly tilt and swirl the pan to coat and cook until the bottom is golden brown and the top is firm, about 1 minute. Loosen the edges of the crepe with a spatula, then flip with your fingers; cook until lightly browned on the other side, 30 more seconds. Invert onto the prepared baking sheet. Repeat with the remaining batter, stacking the crepes as you go; lightly brush the pan with more butter as needed. You will have about 16 crepes. (Don't worry if a few tear-layer them in the middle of your cake.)
Put 1 crepe on a platter and top with a scant 1/4 cup filling, spreading it to the edge. Repeat, stacking the remaining crepes and filling, and ending with a crepe. Refrigerate overnight (this will make slicing easier). Top with whipped cream and orange zest before serving.