Invented by Emma Rylander Lane in the late 19th century, this bourbon-spiked raisin, pecan, and coconut showstopper gets more flavorful with age. Martha made this recipe on episode 707 of Martha Bakes.
Make the cake: Preheat oven to 375 degrees. Butter and flour four 9-inch cake pans. In the bowl of an electric mixer fitted with the paddle attachment, cream together butter, sugar, and vanilla until light and fluffy. Whisk together flour, baking powder, and salt. Add to butter mixture in 3 additions, alternating with the milk.
In a clean mixer bowl, using the whisk attachment, whisk 8 egg whites until stiff but not dry. Fold into cake batter. Divide batter evenly between prepared cake pans. Bake, rotating pans halfway through, until it springs back but has no color on top, 15 minutes. Transfer pans to a wire rack to cool for 15 minutes. Remove cakes from pans, and return to racks to cool completely.
Make the frosting: In the heatproof bowl of an electric mixer set over a pan of simmering water, whisk together yolks, whole eggs, and sugar until thick, glossy, and sugar has dissolved. Transfer bowl to mixer fitted with the whisk attachment and whisk until mixture is cool to the touch, about 10 minutes. Add butter, one piece at a time, whisking until thoroughly combined. Add bourbon and whisk until incorporated. If frosting separates, continue beating until it comes back together, about 5 minutes.
Assemble the cake: Soak raisins in warm water to cover until plumped. Let soak 15 minutes; drain. Place one cake layer on a serving plate. Brush with bourbon to moisten, about 2 tablespoons. Spread with 3/4 cup frosting and top evenly with 1/2 cup raisins and 1/2 cup unsweetened coconut. Repeat process with 2 more cake layers, frosting, raisins, and coconut. Top with remaining cake layer. Brush with remaining bourbon. Spread a thin coat of frosting over the top and sides of cake to cover. Chill for 20 minutes.
Use remaining frosting to cover top and sides of cake. Combine 1 cup each coconut and pecans, and use it to coat the side of the cake. Combine remaining 1/4 cup pecans, 1/2 cup raisins, and 1/4 cup coconut in a bowl. Sprinkle over top of cake to cover. Garnish with kumquats; chill until serving. This cake improves with age and can be made up to 3 weeks in advance. Keep well wrapped in the refrigerator.