Preparation

Prepare the pan:

• 将架子放在烤箱的中间，然后将烤箱加热至350°F。在一个小碗中，将糖与切碎的核桃混合。慷慨地将一个大的邦特锅涂黄油，然后用坚果和糖涂上涂层，用手指按下螺母，以帮助它们粘住。锅的侧面将被覆盖，其中一些坚果将掉到底部 - 很好。

Mix the batter:

• 在一个中等大小的碗中，将面粉，发酵粉，小苏打和盐搅拌直至充分混合。使用电动搅拌机（我使用装有桨附件的厨房辅助工具），打成黄油，糖，香蕉和香草，直到充分混合，香蕉几乎光滑，并根据需要刮下碗的侧面。一次加入一个鸡蛋，跳动直到刚掺入。
• Remove the bowl from the mixer. With a rubber spatula, alternately add half the flour mixture, all the buttermilk, and then the rest of the flour mixture, stirring until each addition is just blended. Spoon half the batter into a medium bowl and gently stir in the melted chocolate until just combined. With a large spoon, alternately add a spoonful of each batter to the prepared pan, working around the pan until all the batter is used. Gently run a knife or the tip of a rubber spatula through the batter, once clockwise and once counterclockwise, to slightly swirl the batters. Gently tap the pan on the counter to settle the ingredients.

Bake the cake:

• Bake until a pick inserted in the center comes out with just a few crumbs sticking to it, about 40 min. Let the cake cool on a wire rack for 15 min. Gently tap the the sides of the pan on the counter and loosen the cake. Invert the pan onto the rack, lift it off the pan, and let the cake cool completely.