Gâteau de crêpes or Gâteau mille-crêpes with Nutella and Chocolate Ganache

Mille is a thousand in French and this classic dessert is a cake made with many crepes.It is a showstopper guaranteed to impress.
Prepare the batter and the pastry cream the day before. Assemble the crepes the day you want to serve the dessert at least 8 hours before you serve it. You can do this dessert with fruit compote, white chocolate ganache or no topping at all, you could use an almond paste instead of Nutella- there are so many combinations. You can garnish the top with fruit, shaved chocolate even edible sugar craft.
Traditionally it is layered with vanilla pastry cream and topped with powdered sugar.

FOR 20 9 inch crepes or buy pre-prepared frozen crepes and thaw them:
6 tablespoons butter
3 cups milk
6 eggs
1 ½ cups flour
7 tablespoons sugar
Pinch salt

FOR THE VANILLA CREAM OR BUY PRE-PREPARED AND KEEP CHILLED:
2 cups milk
1 vanilla bean, halved and scraped
6 egg yolks
½ cup sugar
⅓ cup cornstarch, sifted
3 ½ tablespoons butter

FOR THE ASSEMBLY:
vegetable oil
2 cups heavy cream
1 tablespoon castor or granulated sugar or more
3 tablespoons dark rum (optional)
Icing or Confectioners’ sugar
1 cup Nutella, softened and beaten with a 1/4 cup of warm water
1/2 cup candied hazelnut bits

For the Chocolate Ganache
6 ozs semi sweet chocolate pieces
1.5 cups light cream

You will need- a fine mesh sieve, ice, cold water, crepe pan, small pouring jug, whisks and a large serving platter for assembly, a large 10-12 inch plate and circles of parchment or wax paper to line each crepe.

FOR THE CREPES

In a small saucepan, melt and the butter until bubbly and brown. This browned butter will bring depth of flavour to your dessert. Reserve.
In another saucepan, boil the milk on a medium flame then cool it about 10 minutes. Stir from time to time to prevent a skin from forming. Using a stand or hand whisk beat the salt, eggs and sugar about 2 minutes. Then add the four cup by cup flour until well incorporated. Do not beat excessively. Then slowly add the brown butter and whisk again. Then stir in the warm but not hot milk.
Store this batter in a pouring pitcher or a measuring jug you can use when you have to fry the crepes.

FOE THE PASTRY CREAM
Prepare an ice bath- a large bowl filled with ice that you can put the bowl of pastry cream in to chill it. Over the ice place a clean and empty heat proof bowl for the pastry cream and place a fine sieve over it.
Boil the milk with the vanilla bean and scraped paste in a small saucepan then strain it through a sieve and discard the vanilla pod-you could reuse it if you are doing another dessert immediately after.
In the top pan of a double boiler beat the egg yolks, sugar and cornstarch until smooth then slowly add the the hot milk and combine well. Place pan over the simmering water of the double boiler over high heat and whisking continuously to prevent curdling cook this mixture for 1 to 2 minutes until creamy and thick.
Immediately pour through a sieve into the bowl over the ice bath. Using a spatula squeeze the the pastry cream through the sieve into the bowl over the ice. Stir it several times to cool it and prevent a skin from forming. Then whisk in the butter.
Let the pastry cream cool about 10 minutes, then wrap tightly with plastic wrap-press the wrap down over the surface of the pastry cream to prevent a skin from forming and refrigerate.
GANACHE

Heat the cream in a saucepan until it begins to bubble on medium heat. Switch off the flame and stir in the chocolate until smooth. Cover and reserve.
ASSEMBLY
Remove batter from fridge and let sit 25 minutes. Stir it well and if it has thickened add a 1/4 cup of water to it and stir.
Prepare a plate and your parchment paper sheets. If you have two large baking trays you can use those instead and line both with parchment paper.
Place your 9-inch crepe pan over medium heat. Brush the surface with a teaspoon of oil, then add about 3 tablespoons batter and swirl quickly from side to side to cover the surface. If the pan is too hot the batter will clump. If the batter is too thick it will not spread thinly. The first crepe is the test to gauge your batter.
If the batter is too thick add a little more milk.
Cook the crepe until the bottom begins to brown, about 1 minute. Slide the crepe by moving the pan to ensure it isn’t stuck anywhere then carefully lift an edge and flip the crepe over with a thin spatula. Cook on the other side for 10 seconds. The crepe must not be mushy because you will have trouble picking it up when you have to assemble the cake.
Flip the crepe over onto a baking sheet or plate lined with parchment and let it cool. Repeat until you have 20 round and golden brown crepes.
Remove pastry cream from the fridge and stir well.
Whip the heavy cream with the tablespoon sugar and the rum. Fold it into the pastry cream. Whip the Nutella.
Reserve the best crepes for the bottom and top two layers.
Put down 1 crepe on a flat serving plate. Using an icing spatula, completely cover with a thin layer of pastry cream (about 1/4 cup). Cover with a crepe and spread with Nutella. Repeat to make a stack of 20, 10 pastry cream and 10 with Nutella. Cover and chill for at least 3 hours.
Remove from the fridge and pour the ganache over it. Smooten the top with an icing spatula and allow the rest to drip down over the sides.Garnish with candied hazelnut bits.
Refrigerate for 2 hours.
To serve remove the gateau from the fridge and let sit 30 minutes before you serve it.