Grease and flour an 8-inch (20-cm) springform cake pan.
Preheat oven to 375°F (190°C).
To make cake, put eggs, sugar and lemon peel into a medium bowl.
Beat until pale and creamy, 5 to 10 minutes with an electric mixer.
Sift flour and baking powder together; mix with almonds.
Fold into egg mixture using a metal spoon.
Fold in butter.
Turn batter into prepared cake pan.
Bake 35 to 45 minutes or until a wooden pick inserted in center comes out clean.
Let cake cool overnight on a rack.
Cut cooled cake horizontally into 3 layers.
Join layers together using about half the raspberry jelly.
Preheat oven to 475°F (245°C).
To make topping, put almonds, sugar and egg yolks into a medium bowl.
Add enough rum to give a mixture soft enough to pipe.
Put half the almond mixture into a pastry bag fitted with a fluted nozzle.
Blend remaining almond mixture with enough egg white to give a spreading consistency.
Spread over top and sides of cake.
Pipe mixture in pastry bag over cake in a petal design, as illustrated, making a flower pattern.
Bake cake a few minutes or until almond frosting begins to turn light brown.
Warm remaining raspberry jelly over low heat.
Spoon a little warm jelly into flower petals.
Spread the rest of the jelly over sides of cake; press on sliced almonds.