Flourless chocolate cake

About 10 days ago I had a birthday and, predictably, I prepared a cake with lots of chocolate included. Every day is chocolate day for me, but, of course, there had to be a lot of it for my special occasion. It has intense chocolate flavour and smooth buttery texture. I will keep on searching for the best chocolate-including recipe, but this recipe is close to perfection. 

Ingredients:

For the cake:

• 300 g dark chocolate, chopped
• 200 g unsalted butter, cut into chunks
• 6 eggs, separated
• 1 cup sugar

For the ganache:

• 100 g heavy cream
• 200 g bitter sweet chocolate
• 40 g butter
• 3 Tbsp sugar

Preparation:

Preheat oven to 190°C (370°F) . Butter the bottom of a 20-cm pan. Set aside. 

Cut chocolate into small pieces to enable it to melt quickly and evenly. Put into a small metal bowl, add the butter, cut also into small pieces and melt together in a double broiler, stirring occasionally until the chocolate is melted and smooth. Remove bowl from heat and let the mixture cool for 5-10 minutes. 
Beat the egg yolks, adding slowly 1/2 cup of the sugar until mixture triples in volume. 
Add the melted chocolate. Whisk the egg whites in a clean bowl with clean beaters, adding slowly the second 1/2 cup of sugar. Beat until the egg whites get thick and white. Add slowly egg whites to the chocolate mixture and spoon into the battered pan. Bake for 30-40 minutes and let cool for 15 minutes before inverting it onto a plate. 
Prepare the ganache. Heat the heavy cream on medium heat and add the chopped chocolateq butter and sugar. Stir to incorporate well. Let the mixture cool for 15 minutes and spread over the cake. Sprinkle with chopped walnuts or a colorful decoration. 
This cake tastes better one day after prepared.