BANANA SHEET CAKE WITH PASSION-FRUIT FROSTING

Banana Sheet Cake with Passion-Fruit Frosting image

Provided by Martha Stewart

Time 2h20m

Yield Serves 10 to 12

Number Of Ingredients 15

1 stick unsalted butter, melted and cooled, plus more, softened, for pan
1 2/3 cups unbleached all-purpose flour
1 teaspoon baking powder
1/2 teaspoon baking soda
1 teaspoon kosher salt (we use Diamond Crystal)
4 large eggs, room temperature
1 1/2 cups granulated sugar
3 medium ripe bananas, well mashed (1 cup)
1/2 teaspoon ground cinnamon
2 teaspoons pure vanilla paste or extract
3/4 cup sour cream, room temperature
1 pound cream cheese, room temperature
4 tablespoons unsalted butter, softened
1 1/2 cups confectioners' sugar, sifted
1/4 cup fresh passion-fruit juice (from 4 to 5), plus pulp for serving

Steps:

Cake: Preheat oven to 350°F. Brush a 9-by-13-inch or 8-by-12-inch baking pan with butter. Line with parchment, leaving a 2-inch overhang on long sides. Butter parchment.
Whisk together flour, baking powder, baking soda, and salt. Combine eggs and granulated sugar in the bowl of a mixer fitted with the whisk attachment. Beat on high speed until thick and pale, about 4 minutes. Add flour mixture; beat just to combine. Add butter, bananas, cinnamon, and vanilla; beat to combine. Add sour cream; beat until smooth.
Scrape batter into prepared pan, smoothing top with a spatula. Bake until top springs back when lightly touched and a tester inserted in center comes out clean, 30 to 35 minutes (for 9-by-13-inch) or about 40 minutes (for 8-by-12).
Let cool in pan on a wire rack 10 minutes. Using parchment overhangs, lift cake out of pan and let cool completely on rack. (Cake can be made to this point and stored at room temperature, wrapped in plastic, up to 1 day.)
Frosting: Beat together cream cheese, butter, confectioners' sugar, and passion-fruit juice on medium-high speed until smooth and fluffy, about 5 minutes. Spread over top of cake; drizzle with passion-fruit pulp. Frosted cake is best the day it's assembled, but can be refrigerated, wrapped in plastic, up to 1 day. Return to room temperature before serving.