Gâteau Délice: a chocolate dessert to die for

Preheat the oven to 180°C/350°F. Butter a 20cm cake tin and line it with baking paper.
Beat eggs with sugar and vegetable oil until pale.
In another bowl, whisk together the flour, baking powder, cornstarch and cocoa powder.
Add the dry ingredients to the wet ingredients and mix to combine. Pour the batter into a prepared pan and bake for 40 minutes.
Let the cake cool completely, remove it from the mold and cut it into two equal parts.
For the cream, whisk all ingredients listed together until stiff. Transfer to a piping bag.
Spread a thick layer of hazelnut paste on the bottom layer of the cake, place the cream on top and smooth it with a spatula. Top with another layer of cake.
For the ganache, melt the chocolate and cream in the microwave and pour the ganache over the cake. Spread to cover the sides, then chill the cake until the outer layer is set.