Bananas vary greatly in size. The six bananas called for in this recipe should weigh a total of about four pounds. Once cut, bananas will discolor rapidly, so it’s best to slice them just before using.

　　

Ingredients

makes one 9-inch layer cake

　　1 1/2 sticks (3/4 cup) plus 3 tablespoons unsalted butter, room temperature, plus more for pans

　　2 3/4 cups all-purpose flour, plus more for pans

　　1 1/2 teaspoons baking powder

　　1 teaspoon baking soda

　　1/2 teaspoon salt

　　3 very ripe bananas, mashed, plus 3 ripe bananas, sliced lengthwise, for filling

　　1/4 cup sour cream or crème fraîche

　　1 teaspoon pure vanilla extract

　　1 2/3 cups plus 1/4 cup sugar

　　4 large eggs

　　Mascarpone Frosting (recipe follows)

　　Caramel Sauce (recipe follows)

　　

Mascarpone Frosting

1 pound mascarpone cheese

　　1 1/4 cups heavy cream

　　1/2 cup confectioners’ sugar

　　(makes enough for one 9-inch layer cake, about 4 cups)

　　

Caramel Sauce

1/2 cup sugar

　　1/2 cup heavy cream

　　(makes enough for one 9-inch layer cake)

　　

Step 1

Preheat the oven to 350°F. Butter two 9-by-2-inch round cake pans; line bottoms with parchment. Butter parchment and dust with flour, tapping out excess; set aside. Into a medium bowl, sift together flour, baking powder, baking soda, and salt. In a small bowl, stir together mashed bananas, sour cream, and vanilla; set aside.

　　

Step 2

In the bowl of an electric mixer fitted with the paddle attachment, beat 1 1/2 sticks butter and 1 2/3 cups sugar on medium-high speed until light and fluffy, 3 to 4 minutes, scraping down the sides of the bowl as needed. Add the eggs, one at a time, beating well after each addition. With mixer on low speed, add the flour mixture in two parts, beating until combined after each, 2 to 3 minutes. Using a rubber spatula, fold in the reserved banana mixture, being careful not to overmix.

　　

Step 3

Divide the batter between the prepared pans. Bake, rotating the pans halfway through, until cakes are golden brown and a cake tester inserted in the centers comes out clean, 30 to 35 minutes. Transfer pans to a wire rack to cool 20 minutes. Invert cakes onto the rack; peel off the parchment. Reinvert cakes, and let them cool completely, top sides up.

　　

Step 4

Sprinkle remaining 1/4 cup sugar into a large skillet; cook over high heat, shaking the pan occasionally, until sugar is caramelized. Remove from heat; stir in remaining 3 tablespoons butter until melted. Return pan to medium heat. Add the sliced bananas; cook until slices start to brown, 1 to 2 minutes. Gently turn the bananas, and cook over medium-high heat until browned, about 2 minutes more.

　　

Step 5

Using a serrated knife, trim tops of layers to make level. Place one layer on a cake plate; arrange caramelized banana slices on top. Place remaining layer on top. Using a large offset spatula, spread Mascarpone Frosting over entire cake, swirling to completely cover. Drizzle Caramel Sauce over the top of the cake, or serve some alongside each slice. Serve immediately, or refrigerate, covered with a cake dome, for up to 3 days.

　　

Mascarpone Frosting

Step 6

In the bowl of an electric mixer fitted with the paddle attachment, beat the mascarpone, cream, and confectioners’ sugar until medium-soft peaks form, 1 to 2 minutes. Be careful not to overbeat. Use immediately.

　　

Caramel Sauce

Step 7

Prepare an ice bath; set aside. Cook sugar in a medium saucepan over medium-high heat until it starts to melt around edges; then shake pan to melt remaining sugar. Continue to cook, stirring with a wooden spoon, until golden amber, about 3 minutes. Remove from heat. Stirring constantly, add cream in a slow, steady stream (it will spatter). If necessary, return pan to heat for a few seconds, stirring until mixture is smooth. Place caramel in a bowl in the ice bath; let stand until cold, stirring frequently.

　　

Banana Caramel Cake how-To

Step 8

Long slices of banana are added to a skillet of caramel, then browned on both sides.

　　

Step 9

The caramelized bananas are arranged on the bottom layer of banana cake, then covered with the top layer of cake.

　　Reprinted with permission from Martha Stewart's Baking Handbook by Martha Stewart. © 2005 Clarkson Potter