Preheat oven to 210°F (100°C). Prepare two sheets of parchment paper and a round plate or a cake ring of 7 inches/18 cm. Draw circles using a pencil and turn the baking paper over. Place the paper on two baking sheets with drawing down.

To make cake layers, place egg whites with a pinch of salt in the bowl of a stand mixer and beat until soft peaks. Gradually add sugar and beat until stiff peaks. Add the sifted icing sugar and gently mix with a silicone or rubber spatula.

Transfer the meringue into a pastry bag fitted with Ateco plain pastry tip 809. Draw two spiral disks on parchment paper starting from the center. Bake for 2 hours. Let the meringue disks cool down.

To make Biscoff whipped cream, place whipping cream and mascarpone cheese in the cold bowl of a stand mixer with the whisk attachment. Beat ingredients at medium speed, then high speed until "almost done" whipped cream. Add cookie spread and mix at a low speed. Transfer the cream into a piping bag with plain pastry tip 809.

To assemble the cake, place the first meringue layer on a cake board. Pipe the Biscoff cream in a spiral over the first cake layer and spread an even layer using a bent spatula. Place the second layer and repeat with the cream. Smooth the sides of the cake with the remaining cream.

Cover the entire cake with crushed Biscoff cookies. If desired, whip up plain whipped cream and pipe a few swirls using an open star tip (Wilton M1). Refrigerate the cake for 3-4 hours before serving.