Preheat oven (electric cooker: 140 °C/circulating air: 120 °C/gas: see manufacturer). Line a springform pan (26 cm Ø) with baking paper. Beat the egg whites until stiff and add 2 tbsp. sugar. Whip cream until stiff. Eggs and 100 g sugar
Chopping chocolate. Heat milk with lemon peel in a pot and remove from the heat. Melt chocolate in it while stirring. Stir in 50 g cocoa * stir the chocolate mixture into the egg-sugar cream by the spoonful. First fold cream, then beaten egg white in 2 portions into the chocolate cream. Fill into the mould and smooth it down. Bake in a hot oven for about 1 hour.
Open the oven door a little and let the chocolate cake cool down for about 30 minutes. Take out and let it cool down. Keep cake cold until serving. Dust with a little cocoa and decorate with gold leaf as desired.