Preheat oven to 180 degrees C and grease a round tin.
Empty the container of yoghurt in a mixing bowl and add the 3 eggs and 1 1/2 yoghurt container's worth of sugar. Beat until frothy and pale, then add flour and baking powder. Once mixed, stir in the vegetable oil.
Pour the batter into the prepared cake tin and bake 40 minutes or until a skewer tests clean. Let cool 10 minutes, then remove cake and cool on a rack.
Meanwhile, whip the cream. When it begins to thicken, beat in the icing sugar until firm. Add the hazelnuts and stir gently. Set aside.
Once the cake is cool, cut into two disks, the bottom one being thicker than the top. Place the top half on a cutting board and cut out the centre with a wide glass, to make a ring.
Spread 3/4 of the whipped cream on the bottom half and cover with the top to make a nest.
Ice the cake: melt the chocolate in a microwave with 1 teaspoon water, stirring regularly until smooth and shiny. Spread carefully over the top of the cake. Spread the remaining whipped cream over the sides.
For a more realistic effect, sprinkle the cake with shaved chocolate. Fill with chocolate eggs and dazzle your guests!