To make sponge cake: preheat oven to 350-degrees F. Butter and flour a 9-inch round cake pan. In a large mixing bowl beat egg yolks until light. Beat in 1/2 cup sugar until mixture forms ribbons when beaters are lifted. Sift flour with baking powder and then fold it into batter in 3 batches -- the batter will be stiff. Stir in extract. In a clean mixing bowl, beat egg whites and cream of tartar until soft peaks form. Beat in 1/4 cup sugar until peaks are stiff. Fold egg white mixture into egg yolk/flour mixture. Pour into prepared pan. Bake for 35-40 minutes or until golden and tester comes out clean. Invert onto rack cool but do not remove pan until cooled. Run a knife around edge of cake and invert cake onto platter.
To make custard: in a saucepan whisk together yolks, sugar and flour until smooth. Whisk in milk. Stir in lemon peel. Stir over medium low heat until mixture boils. Pour into glass or plastic bowl, discarding lemon peel. Stir in vanilla. Cool.
To assemble cake: divide custard among three bowls. In one bowl stir in chopped almonds. In the second bowl stir in cocoa powder. The third is left plain.
Cut cake horizontally into three layers using a serrated knife.
Set one layer on platter and sprinkle with rum and spread with the almond custard.
Top with second layer. Sprinkle with rum and spread with plain custard.
Top with final layer. Sprinkle with orange liquour (or juice) and spread top and sides with cocoa custard, smoothing evenly.
Sprinkle flat side of ladyfingers with rum or orange liquor (or juice) and press ladyfingers around cake, rounded side out. Decorate wth 2 almonds on top of cake.