I found myself a few weeks ago with a supply of over-ripe bananas. I like my bananas with sugar spots, but these were too far gone even for me, so I let them continue to ripen until they were black.
I had intended to make banana bread until I saw a recipe for a banana cake in the February issue of Gourmet. This cake is tasty enough that it's worth letting some bananas go bad just to create the main ingredient. The texture and density are closer to banana bread than to cake, but yogurt keeps it moist and crumbly. The nuts, chocolate and hint of cinnamon make it interesting.
The cake is versatile enough to be used for dessert or brunch. It's better the day after it has been baked, though. I stored it in an airtight plastic container, and it became moister as it aged.
Bananas are ready to be used in baking when they are black but not yet moldy. The ripening process will speed up if the bananas are stored in a warm place. I've also heard of people zapping them in the microwave.
Following is the recipe as I prepared it, which differs slightly from the original.
Banana Chocolate Walnut Cake
2 1/4 cups all-purpose flour
1 teaspoon baking soda
1/2 teaspoon salt
1 stick unsalted butter, softened, plus 2 tablespoons melted and cooled
1 cup sugar, divided
2 large eggs
1 1/4 cups mashed very ripe bananas (about 3 medium)
2/3 cup plain whole milk yogurt
1 teaspoon pure vanilla extract
1/2 cup semisweet chocolate chips
1 cup walnut pieces, coarsely chopped
1/2 teaspoon cinnamon
Preheat over to 375 degrees, with rack in the middle. Butter a 9-inch round cake pan.
Stir together flour, baking soda and salt.
Beat together 1 softened stick of butter and 3/4 cup sugar in a medium bowl with an electric mixer at medium speed, until pale and fluffy, then beat in eggs 1 at a time until blended. Beat in bananas, yogurt and vanilla (mixture will look curdled).
With mixer at low speed, add flour mixture and mix until just incorporated.
Toss together chocolate, nuts, cinnamon, melted butter and remaining 1/4 cup sugar in a small bowl.
Spread half of banana batter in cake pan and sprinkle with half of chocolate mixture. Spread remaining batter evenly over filling and sprinkle remaining chocolate mixture on top.
Bake until cake is golden and a wooden toothpick inserted in the cake without making contact with chocolate comes out clean, 35 to 40 minutes. Cool cake in pan on a rack 30 minutes, then turn out onto rack and cook completely, right side up.