For the cake: preheat the oven to 175°C/350°F. Butter three 9-inch round cake pans or coat with vegetable cooking spray. Line the bottom of each with parchment or waxed paper and grease the paper. Combine the chocolate and buttermilk in a double boiler or a metal bowl set over a pan of simmering water. Heat, stirring often, until the chocolate melts, about 7 minutes; do not let the buttermilk come near a boil, or it will curdle. Remove from the heat and whisk until smooth. In a large mixing bowl, whisk the eggs lightly. Beat in the oil and vanilla. Gradually whisk in the sugar until well blended. Stir in the melted chocolate mixture and whisk until smooth and homogenized. Sift together the flour, cocoa powder, baking soda and cinnamon. Set these dry ingredients aside. In 2 or 3 alternating additions, add the dry ingredients and cola to the chocolate mixture, beating well between additions. Divide the batter among the 3 prepared pans. Bake for approximately 25 minutes (mine baked for 35) or until a cake tester or wooden toothpick inserted in the center comes out clean. Let the layers cool in their pans for 10 minutes then turn onto wire racks to cool completely, at least 1 hour. Make the frosting: preheat the oven to 175°C/350°F. On a baking sheet, spread out the coconut in an even layer. Toast in the oven for 5-7 minutes, tossing once, until the coconut is very lightly browned. Transfer to a dish and let cool. Repeat the process with the almonds. Leave the oven on. Spoon the condensed milk into a heatproof glass baking dish, cover tightly with foil and set the dish in a roasting pan or larger baking dish. Fill the pan with enough hot water to reach about halfway up the side of the smaller baking dish. Bake for 2 hours, stirring once or twice, until the milk is a light caramel color. Carefully remove the dish from the water bath and remove the foil with caution; the hot steam can burn. Transfer the caramelized milk to a bowl and whisk until smooth. Stir in the toasted coconut and almonds (I saved a little to sprinkle the cake). Let cool slightly. Cover the frosting with plastic wrap, pressing it directly onto the surface, then refrigerate until cool but not set, 1 to 1 ½ hours. To assemble the cake, place one layer, flat side up, on a cake plate or stand. Cover the top with about ¾ cup of the frosting, spreading evenly to the edge. Repeat with the second layer and another ¾ cup frosting. Finally, spread the remaining frosting over the top of the cake, allowing the excess to decoratively down the sides. Refrigerate the cake, uncovered, for at least 1 hour, until the frosting sets. Then cover with a cake dome, large bowl or plastic wrap until ready to serve. This allows the moisture to even out and prevents the frosting from forming a crust. Chilling also makes the cake easier to cut, something that’s best done with a hot, wet serrated knife – this is an unbelievable tender cake. * we can’t find buttermilk here in Brazil, so I used the following mixture instead: 1 tablespoon white vinegar plus enough milk to equal 1 cup for 1 cup of buttermilk; let stand 5 minutes. ** the same thing happens with cake flour, so I used the following: 1 cup cake flour = ⅞ cup all purpose flour + 2 tablespoons corn starch
