In a bowl, beat 2 egg yolks and 1/3 cup sugar until light and fluffy. Add in mascarpone until no lumps are seen.
In a stand mixer fitted with the whisk attachment, beat egg whites until soft peaks form. Fold these egg whites gently into mascarpone mixture.
Pour espresso into a shallow bowl. One at a time, gently but quickly dip biscoff biscuits into the espresso. Do not oversaturate or it will become soggy. Arrange the dipped biscoff biscuits into a deep dish to form a solid layer. If necessary, cut biscoff biscuits to fill any gaps in the layer.
Pour about 1/3* of the mascarpone mixture on top of the biscoff layer. You may pour more or less depending on the size of your dish and how many layers you desire.
Repeat steps 3 and 4 to form multiple layers. I aim to make 2-3 layers.
In a stand mixer with the whisk attachment, beat 1/2 cup heavy cream and 1 tbsp sugar until stiff peaks form. Pipe or spread whipped cream on top.
Dust whipped cream with cocoa powder. Sprinkle chocolate shavings on top as desired. Refrigerate for at least 2 hours, preferably overnight.