German Chocolate Cake with Banana, Macadamia, and Coconut Filling | America's Test Kitchen

Ingredients

• 4 egg yolks
• 1 can evaporated milk (12 ounces)
• 1 cup granulated sugar (7 ounces/198 grams)
• 1/4 cup packed light brown sugar (1 3/4 ounces/50 grams)
• 6 tablespoons unsalted butter (3/4 stick), cut into 6 pieces
• 1/8 teaspoon table salt
• 1 teaspoons vanilla extract
• 2 teaspoons dark rum
• 2 1/3 cups sweetened shredded coconut (7 ounces/198 grams)
• 1 1/2 cups roasted unsalted macadamia nuts (6 1/2 ounces/184 grams), finely chopped and toasted on baking sheet in 350-degree oven until fragrant and browned, about 8 minutes
• 4 medium bananas , cut into 3/8-inch-thick slices
• 4 ounces (113 grams) semisweet or bittersweet chocolate , chopped fine
• 1/4 cup Dutch-processed cocoa , sifted
• 1/2 cup boiling water
• 2 cups unbleached all-purpose flour (10 ounces/283 grams), plus additional for dusting cake pans
• 3/4 teaspoon baking soda
• 12 tablespoons unsalted butter (1 1/2 sticks), softened
• 2/3 cup packed light brown sugar (about 4 3/4 ounce/135 grams)
• 3/4 teaspoon table salt
• 4 large eggs , room temperature
• 1 teaspoon vanilla extract
• 3/4 cup sour cream , room temperature