Preheat oven to 325 degrees Grease and flour 2 nine inch cake pans and line the bottoms with parchment paper if you like, to help prevent sticking.

Sift together the cake flour, baking powder and salt and set aside.

Cream together the butter and sugar until fluffy.

Add the eggs, one at a time, beating well after every addition.

Mix in the orange zest.

Beat in the vanilla extract.

Gently fold in the dry ingredients in three equal portions, alternately with the evaporated milk

When adding dry and wet ingredients alternately in any baking recipe, always begin and end with the dry ingredients. I generally fold the dry ingredients in 3 portions and the milk in 2 portions.

Spread the batter evenly into the prepared cake pans. Bake in a 325 degree F oven for about 35-40 minutes or until a toothpick inserted in the center comes out clean. Watch it carefully, you will not want to overbake this cake, as soon as the toothpick comes out clean, remove the cake from the oven and let it rest in the pans for 5 minutes before turning it out onto a wire rack to cool completely.

Heat 1 cup of the whipping cream in a double boiler over a gentle simmer until almost scalded.

Add the chocolate chips and stir constantly,  just until the chocolate is melted and smooth throughout. You do not want this mixture to get very hot, it should be just at the melting point and only lukewarm to the touch.

In a separate bowl, whip the remaining 3 cups of whipping cream to firm peaks.

Add the whipped cream to the chocolate mixture in four portions, folding gently after each addition until the whipped cream is completely incorporated into the chocolate.

At this point you will probably have to chill this frosting for a half hour or so in the fridge if it is too soft to work with. Just give it a quick fold with a rubber spatula every 10 minutes so that it cools evenly in the fridge.

Fill and frost the cake layers with the frosting and garnish with orange slices if desired. Chill the cake for a couple of hours before serving.