Preheat oven to 325°F and arrange rack in center of oven.

Butter the bottom and sides of a 9 by 2 inch round cake pan and line with parchment paper.

Melt butter and semi-sweet chocolate chips over a double boiler until smooth. Cool slightly.

Whip eggs and salt for 5 minutes in a large bowl. Gently fold the eggs into the chocolate, one third at a time.

Pour the batter into cake pan. Put in a water bath by placing the cake pan in a larger cake pan and fill large cakepan halfaway up the sides with hot water.

Bake for about 40 minutes. Remove from water bath and let cool completely in pan. Refridgerate overnight. Run a metal spatula along the sides to remove from pan.

For ganache: bring heavy cream to a simmer over low heat and pour over milk chocolate chips. Let cool until warm and pour over cake. Chill cake for 30 minutes. Garnish with white chocolate shavings.