Cut butter and chocolate into pieces and melt in a double boiler.
Preheat oven to 390°F.
Coat inside of a 20 cm springform pan with butter and sugar.
Finely chop Hojiblanca black olives.
Beat eggs and superfine sugar with a mixer until a compact mousse forms. Add melted chocolate and chopped Hojiblanca black olives with a spatula and gently fold in flour.
Pour mixture into pan. Bake for about 12 minutes. Remove pan from oven and place on a rack.
Finely chop Hojiblanca black olives.
In a heavy-bottomed skillet, melt one cup of superfine sugar until it becomes caramel in colour. Add whipping cream and reduce.
Remove from heat, add butter, and mix well to melt butter.
Add chopped Hojiblanca black olives and pour sauce into a jar.
Serve cake in pan with a spoon. Serve caramel sauce separately.