Kiev cake (hazelnut and butter cake)

Instructions

1. Toast the hazelnuts at 180 °C for 10 minutes, then blend them finely with the flour.
2. Whisk the egg whites with the vinegar, then gradually add the sugar until you get a glossy, firm meringue.
3. Gently fold the hazelnut powder and flour into the meringue with a spatula.
4. Spread the mixture into 3 discs on baking paper and bake at 140 °C for 50 minutes.
5. Let the meringue discs cool completely.
6. Make the buttercream by whisking the softened butter with the icing sugar, milk and vanilla until fluffy.
7. Assemble the cake by alternating meringue and buttercream, then smooth the sides.
8. Melt the chocolate with the cream, coat the top of the cake and chill for 1 hour.