Preheat the oven to 350 degrees F. Grease
a 10-inch cake pan
and line the bottom with parchment paper.
Combine the 20 amaretti cookies and the chocolate in a food processor
. Run the machine until the mixture is very finely minced. Set aside.
Using an electric mixer
and a large bowl, cream together the butter and sugar
until pale yellow, about 2 minutes. Add the egg yolks 1 at a time, incorporating each yolk before adding the next. Once all the eggs are added continue to cream
the mixture together until light and fluffy, about 4 more minutes. Add the orange liqueur
. With the machine on low, add the flour and the chocolate amaretti mixture. Mix well after each addition.
In medium bowl whip
the egg whites using an electric mixer until stiff peaks form, about 3 minutes. Add 1/3 of the whipped egg whites into the cake mixture until well combined. Gently fold in the remaining whipped egg whites. Pour the batter
into the prepared cake pan. Bake until a toothpick comes out clean, about 45 to 50 minutes.
Let the cake cool in the pan on a wire rack for 10 minutes. Turn the cake out onto a platter and continue to cool to room temperature. Top with the orange marmalade
in an even layer. Sprinkle the remaining crushed amaretti
cookies over the top of the cake. Slice and serve.