Banana And Chocolate Marble Crunch Cake

For the crumbs: Stir the flour, cocoa powder and sugar together in a small bowl. Stir in the melted butter until crumbs form. Set aside.

For the cake: Preheat the oven to 325 degrees F. Butter the bottom and sides of a 9-by-9-by-2-inch pan.

Sift the flour, baking powder, salt and cinnamon together. Set aside.

Beat the butter and sugar in the large bowl of an electric mixer on medium speed until fluffy, about 2 minutes. Add the eggs and vanilla, then beat for 1 minute.

In a separate bowl, gently stir the baking soda into the sour cream. Stir the mashed bananas into the sour-cream mixture.

On low speed, add the flour mixture to the butter mixture in 3 additions alternating with the banana mixture, beginning and ending with the flour mixture. Mix just until the last addition of flour is incorporated.

Put 1 cup of the batter in a small bowl and stir in the melted chocolate.

Spread half of the plain batter in the pan. Spoon the chocolate batter evenly over the batter in the pan. Spread the remaining plain batter evenly over the chocolate batter. Dip a spatula in the batter and draw it around the pan to marbleize the chocolate slightly.

Sprinkle the reserved chocolate crumbs evenly over the batter.

Bake in the preheated oven until a toothpick inserted into the center of the cake comes out clean, about 50 minutes.

Cool the cake thoroughly in the baking pan on a wire rack.

Cut the cake into squares and serve.