For Crepe base:
4 eggs, at room temperature
1/4 teaspoon salt
2 cups flour
2 1/4 cups milk, at room temperature
1/4 cup (1/2) stick unsalted butter, melted

For chocolate-hazelnut filling:
1 1/3 cups heavy whipping cream
3 tablespoons unsweetened cocoa powder
3 tablespoons vanilla sugar
1 teaspoon vanilla extract
2 tablespoons Frangelico hazelnut liqueur

For chocolate-hazelnut ganache:
3.5 ounces semisweet or bittersweet chocolate
1/2 cup heavy cream
1 tablespoon Frangelico hazelnut liqueur