Wash and dry fruit, then put through food processor to chop. Soak in 3/4 c rum in covered container for at least three weeks, stirring every few days. When ready, make cake:
Heat 1 pound brown sugar in heavy bottomed frying pan until melted; simmer until dark dark dark brown. Let cool (If you live in a city, you can probably find "burnt sugar" in specialty markets like West Indies, and some Latin markets. The commercial sugar makes a blacker cake.
Cream butter and remaining brown sugar. Add eggs a little at a time. Add soaked fruits with their liquid, and enough caramelized sugar to make it as dark as desired. Add dry ingredients and nuts.Pour batter into 9 or 10" springform pan, greased and bottom lined with waxed paper. Bake at 300 degrees for about 2 to 2 1/2 hours. Sprinkle some of the remaining 1/4 cup rum over cake immediately after removing it from the oven. Repeat a few times. Allow cake to remain in pan for 2-3 days.
Icing The Cake
Remove cake from pan and place on cake plate. Roll out almond paste to a circle big enough to drape over the cake, covering top and sides. Smooth tightly over the cake and trim bottom edges. Allow to dry for a day before adding royal icing.Make Royal Icing (this is an icing that becomes quite hard): Beat 2 egg whites to a froth. Add 1 pound confectioner's sugar, a little at a time on low speed. Add juice of one lemon and continue beating until stiff peaks form.
Using a knife dipped in hot water, spread icing over the almond paste. Do Not Leave Unused Icing Unattended...If You Have To Stop, Make Sure It Is Covered With Damp Paper Towels, Or Covered And Refrigerated. This icing hardens and dries up quickly. A second layer of icing may be applied when the first has dried. Decorate as desired.