Preheat the oven to 375°F, then grease and line two 9-inch cake pans with parchment rounds.

In a mixing bowl, combine the sifted cake flour, baking powder, and salt, then set aside.

In a large mixing bowl, cream the softened butter and 1 1/2 cups granulated sugar until pale and fluffy, then stir in the vanilla extract and almond extract.

Stir together the buttermilk and 1/2 cup water, then add the buttermilk mixture and flour mixture to the butter mixture alternately, about one-third at a time, mixing between additions until a thick batter forms.

In a clean bowl, beat the 3 egg whites until stiff peaks form, then gently fold them into the cake batter just until combined.

Divide the batter evenly between the prepared pans, smooth the tops, and bake for about 30 minutes, or until a knife inserted into the center comes out clean.

Let the cakes cool in their pans for 15 minutes, then turn them out onto cooling racks and let them cool completely.

Combine the chopped raisins, diced dates, 1/2 cup water, and honey in a small saucepan, heat over medium heat until bubbling, and cook until the liquid has been absorbed into the fruit.

Remove the pan from the heat, stir in the rum extract and chopped walnuts or pecans, and set the filling aside to cool.

Put the 2 cups sugar, salt, cream of tartar, 4 egg whites, and 1/4 cup water into a clean saucepan set over medium-low heat, then beat continuously with an electric mixer for 5 to 7 minutes, until the sugar has dissolved and the frosting reaches stiff peaks.

Remove the frosting from the heat once it is thick, glossy, and holding stiff peaks, then fold in the 2 teaspoons vanilla extract.

Reserve 1/2 cup of frosting and stir it into the cooled fruit-and-nut filling to make it lighter and easier to spread.

Level the cooled cake layers by trimming away any uneven domes, then use the two layers as they are or carefully slice each layer in half horizontally to make four thinner layers.

Place one cake layer on a serving plate or cake stand, spread fruit filling over the top, and continue layering cake and filling until the filling is used, ending with a cake layer on top.

Frost the top and sides generously with the remaining frosting, use the back of a spoon to make soft peaks and swirls, sprinkle with extra chopped nuts if desired, then slice and serve.