3 ripe bananas, plus 1 to 2 more for garnish
3/4 cup sugar
2 cups cake flour (not self-rising), sifted
3 large eggs, separated
1/2 teaspoon baking soda
1/2 cup sour cream
1/2 teaspoon baking powder
1 teaspoon pure vanilla extract
3/4 teaspoon salt Honey-Cinnamon Frosting (see below)
1/2 cup (1 stick) unsalted butter, room temperature
2 1/2 cups confectioners' sugar, sifted
1/4 teaspoon ground cinnamon
2 tablespoons honey
1 cup (2 sticks) unsalted butter, room temperature
Preheat oven to 400 degrees F. Line standard muffin tins with paper liners. Place 3 whole unpeeled bananas on a baking sheet and roast 15 minutes (the peels will darken). Meanwhile, sift together cake flour, baking soda, baking powder, and salt.
Remove bananas from oven and let cool before peeling. Reduce oven temperature to 350 degrees F
With an electric mixer on medium--high speed, cream butter and sugar until pale and fluffy. Add egg yolks, one at a time, beating until each is incorporated, scraping down sides of bowl as needed. Add roasted bananas, and beat to combine.
Add flour mixture in three batches, alternating with two additions of sour cream, and beating until just combined after each. Beat in vanilla.
In another mixing bowl, with electric mixer on medium speed, whisk egg whites to soft peaks; fold one-third whites into batter to lighten. Gently fold in remaining whites in two batches.
Divide batter evenly among lined cups, filling each three-quarters full. Bake, rotating tins halfway through, until a cake tester inserted in centers comes out clean, about 20 minutes. Transfer tins to wire racks to cool completely.
To finish, fill a pastry bag fitted with a medium French-star tip with frosting. Pipe seven scallops around perimeter of cupcake, and pipe a large starburst in the center. Just before serving, thinly slice remaining bananas, and place 2 slices on top.
With an electric mixer on medium speed, beat all ingredients until smooth.
Use immediately, or refrigerate up to 5 days in an airtight container; before using, bring to room temperature and beat until smooth.