| | CAKE |
| 2 1/4 | c | Cake flour (not self-rising), spooned lightly into measuring cups |
| 1 1/2 | ts | Baking powder |
| 1 1/2 | ts | Baking soda |
| 1/4 | ts | Salt |
| 3/4 | c | (1 1/2 sticks) unsalted butter, softened |
| 1 1/2 | c | Sugar |
| 3 | lg | Eggs |
| 2 | ts | Pure vanilla extract |
| 3/4 | | Generous cup very ripe mashed bananas (about 2) |
| 1/4 | c | Plus |
| 2 | tb | Sour cream or plain yogurt |
| | Confectioner's sugar, for sprinkling (optional) |
| | CHOCOLATE FROSTING (OPTIONAL): |
| 1 1/2 | c | Sifted confectioners' sugar |
| 3 | oz | Unsweetened chocolate, melted |
| 2 | tb | Sour cream, or more as needed |
| 2 | tb | Unsalted butter, softened |
| 1/8 | ts | Salt |
| 1 | ts | Pure vanilla extract |
