Step 1

Preheat the oven to 350 degrees F and line a 9-by-13-inch baking pan (see Cook's Note) with aluminum foil, leaving a 2-inch overhang on the two longer sides. Lightly spray the foil with nonstick cooking spray.

Step 2

For the cake, mash the bananas in a large bowl with a fork or potato masher until very smooth. Whisk in the dark brown sugar, melted butter, sour cream, eggs and vanilla until smooth and combined. In a separate large bowl, whisk together the flour, cinnamon, baking soda and salt.

Step 3

Fold the dry ingredients into the banana mixture in thirds until just combined. Pour into the prepared baking pan and smooth the top. Bake until golden brown and a toothpick inserted into the center comes out clean, about 1 hour. Leave the cake in the pan to cool slightly, about 30 minutes. Use the foil overhang to remove the cake from the pan, then transfer to a wire rack to cool completely.

Step 4

Meanwhile, beat the butter, cream cheese and salt in a large bowl with an electric mixer on medium speed until smooth. Reduce to low speed, then add the powdered sugar a cup at a time until smooth. Increase the speed to medium-high and beat until fluffy, 1 to 2 minutes. Beat in the vanilla extract.

Step 5

Transfer 1/2 cup of the frosting to a small bowl and stir in the dulce de leche until smooth. Cover both frostings with plastic wrap and keep at room temperature until ready to assemble the cake.

Step 6

For the candied banana chips, warm the maple syrup in a medium nonstick skillet over medium heat until it just starts bubbling. Add the banana chips and cook, tossing and stirring frequently with a rubber spatula, until the chips have absorbed almost all the maple syrup and are browned in spots, 3 to 4 minutes. Immediately transfer the banana chips to a baking sheet, spread in an even layer and cool completely. Once cool, roughly chop.

Step 7

Transfer the cake to a serving platter. Spread about 3/4 cup plain cream cheese frosting all over the top of the cake.

Step 8

Dollop the dulce de leche frosting and remaining plain frosting on top, then use a small offset spatula to swirl both frostings together in a swooping design, making sure the frosting goes all the way to the edges of the cake. Top with the chopped candied banana chips.