* plus extra for pan.

For the topping: Put the banana chips between 2 pieces of wax paper and crush them into approximately 1/2-inch pieces with a rolling pin or the flat side of a meat pounder. You should have about 3/4 cup banana chips pieces. Melt the butter and brown sugar in a small saucepan over medium heat. Bring the mixture to a boil and cook for 30 seconds, stirring constantly. Remove the pan from the heat and stir in the banana chips and chopped pecans until they are well coated with the brown sugar mixture. Set aside.

Position an oven rack in the middle of the oven. Preheat the oven to 325 F. Butter the bottom and sides of a 2-inch deep, 9-inch layer pan. Line the bottom of the pan with parchment or wax paper and butter the paper.

For the cake: Sift the flour, baking powder, salt and cinnamon together. Set aside. Put the 6 tablespoons softened butter in the large bowl of an electric mixer and beat on medium speed 15 seconds. Slowly add the sugar and beat 2 minutes. The mixture will be thick. Add the eggs and beat for 1 minute. Stop the mixer and scrape the bowl's sides down once during this beating. Add the vanilla and rum.

Gently stir the baking soda into the sour cream. Stir the sour cream mixture into the mashed bananas. The banana mixture will be lumpy. Decrease the mixer's speed to low and add the flour mixture and the banana mixture alternately, beginning and ending with the flour mixture (3 additions of flour, 2 of banana). Stop mixing as soon as the last addition of flour is incorporated.

Spread half the batter in the prepared pan. Sprinkle 1/2 cup of the topping evenly over the batter. Spread the remaining batter evenly over the topping. Sprinkle the remaining banana crunch topping evenly over the batter. Bake in the preheated oven until a toothpick inserted into the center of the cake comes out clean, about 1 hour. Cool the cake in the pan on a wire cooling rack for about 2 hours. Use a small sharp knife to loosen the sides of the cake from the pan. Place a flat plate on top of the cake and invert the cake onto the plate. Carefully remove and discard the paper liner. Place another flat plate or a moisture-resistant cardboard cake circle on the bottom of the cake and invert the cake. The cake is now right-side up. Replace any of the topping that may have fallen off the top.

To freeze: Wrap the cooled cake tightly with plastic wrap then heavy aluminum foil. Label with date and contents. Freeze up to 3 months.

Serves 10.