Grease and flour a 12-inch (30-cm) long Balmoral pan or a 12x4-inch (30x10-cm) loaf pan.
Preheat oven to 350°F (175°C).
Cream butter and sugar in a medium bowl until light and fluffy.
Melt 4 oz.(100 g) chocolate in a double boiler over low heat.
Add to butter mixture with egg yolks.
Beat mixture until very creamy.
Stir in ground almonds, cookie crumbs and flour.
Beat egg whites until stiff; fold into chocolate mixture.
Turn batter into pan.
Bake 50 to 60 minutes or until a wooden pick inserted in center comes out clean.
Turn out cake onto a rack to cool.
Press slivered almonds into cake as illustrated.
Melt 4 oz.(100 g) chocolate in a double boiler over low heat.
Cover cooled cake with chocolate.