Step 1

Beat the egg whites with the salt and cream of tartar until stiff and shiny. Add the sugar, constantly beating, spoonful at a time, until very shiny, and you cannot feel any sugar granules between fingers. Add vanilla and almond extract. Fold in the ground almonds and hazelnuts. Line two baking trays with parchment paper and spread the meringue into four 30x10 cm (12 x 4-inch) rectangles, two rectangles on each baking tray. Bake the meringues in a 120°C/250°F oven for an hour, rotating the pans halfway through. Take them out of the oven and let them chill on a wire rack.

Step 2

Soak the apricots in the water and vermouth overnight or for a few hours. Transfer to a pot, add the cinnamon and orange zest, and simmer for 10 minutes until the apricots are tender. Drain the apricots and save the liquid. Remove the cinnamon stick and puree the fruit in a blender or a food processor. Reduce the cooking liquid until thick and stir in the puree and the liqueurs. Refrigerate covered until chilled.

Step 3

Beat the room temperature butter with sugar until light and fluffy. Add the egg yolks and beat for another minute, then add the vanilla and liqueur. Let cool in the fridge and beat again before assembling.

Step 4

You will need only three meringue layers of four, so save the best-looking one for the top. Spread one-third of the buttercream on the bottom meringue layer. Cover it with a second meringue layer, then spread that one with the apricot cream. Place the best-looking meringue layer on top and spread the rest of the buttercream over the top and the sides of the cake. Press the slivered almonds into the sides of the cake. Refrigerate until serving time.

Step 5

Before serving, sprinkle the top of the cake with confectioners' sugar.