For the cream
4 tablespoons all-purpose flour
2 cups milk
4 tablespoons cornstarch
1 egg
1 cup heavy cream, 1 tablespoon vanilla extract
For the dough
6 eggs (separated)
8 tablespoons all-purpose flour
1 teaspoon baking powder
4 tablespoons sweet potato flour, Melted butter for greasing, Wheat flour and confectioner's sugar for dusting
For the cream
4 tablespoons all-purpose flour
2 cups milk
4 tablespoons cornstarch
1 egg
1 cup heavy cream, 1 tablespoon vanilla extract
For the dough
6 eggs (separated)
8 tablespoons all-purpose flour
1 teaspoon baking powder
4 tablespoons sweet potato flour, Melted butter for greasing, Wheat flour and confectioner's sugar for dusting
Prepare the cream
In a saucepan, whisk together the flour and milk
Add the cornstarch and egg, whisking constantly until thickened
Add the heavy cream and vanilla extract
Set aside, covered with plastic wrap, stuck to the cream
Prepare the dough
In an electric mixer, beat the egg whites until stiff peaks form
Add the yolks one at a time, beating until smooth
Add the flour, whisking until just combined
Misture delicately the baking powder and sweet potato flour panned
In a 31 x 45 cm baking dish, greased with butter and dusted with wheat flour, bake in a preheated moderate oven (180°C), central rack, for 10 minutes or until golden brown
Turn out onto a floured cloth
Fill, leaving 1 cm borders
Roll up, pressing gently, along the longer side
Dust with confectioner's sugar, sharpening knife and toast the edges forming diamonds
Refrigerate for one hour
Slice with a serrated knife
Serve.
