This is a serious childhood throwback for me. I have a memory of my mother taking this out of the oven and I could smell the chocolate and the almonds more than anything else. So delicious.
Preheat the oven to 375 degrees F. Use the butter to thoroughly grease the bottom and sides of a 1 quart loaf pan.
Add the 2 whole eggs to a small pot and cover them with cold water. Bring the water to a gentle boil over medium heat. When the water boils, lower the heat to a simmer and cook the eggs for 6 minutes. Remove the eggs from the pot and run them under cold water to stop them from overcooking.
In a medium bowl add the ricotta and whisk until free of lumps. Add the sugar, rum, chocolate and almonds and stir to blend. Set aside.
Peel the hard-boiled eggs and put the yolks through a small strainer to break them into small bits. Add the egg yolks to the ricotta mixture.
In the bowl of an electric mixer fitted with a whisk attachment, add the 2 egg whites and beat until stiff peaks form, about 3 to 5 minutes. Gently fold the egg whites into the ricotta mixture with a rubber spatula, retaining as much fluffiness as possible. Transfer the mixture to the loaf pan. Put the pan into a shallow water bath and bake, undisturbed, for 50 minutes. Remove the pan from the oven and the water bath. Allow to cool 10 to 15 minutes before serving. Sprinkle with a touch of lemon zest and some chocolate over each individual portion.