Chocolate-Hazelnut Banana Bread

Beat the dough with light hands; beating too hard may cause the streaking effect to be lost.
Preheat the oven to 350 degrees.Combine the chocolate-nut paste and 1 teaspoon of butter in a microwave-safe bowl; reheat in the microwave on high power for 30 seconds or until it melts. Mix it up. Combine 3 tablespoons of vegetable oil, butter, brown sugar, and banana in a large bowl; beat with a mixer on medium-high speed until smooth. Add the eggs, 1 at a time, beating well after each addition.Spoon the flour into dry measuring cups; flatten with a knife. Combine flour, baking soda, baking powder, and salt. While whisking on low speed, add the flour mixture and buttermilk alternately to the banana mixture, starting and ending with the flour mixture; beat until smooth. Place half of the dough in a 9-inch x 5-inch metal baking dish greased with baking spray and sprinkle with the chocolate-nut mixture. Spread the remaining dough over the chocolate mixture. Using a wooden pickaxe, beat the dough. Sprinkle the dough with hazelnuts.Bake at 350 ° C for 55 minutes or until you have a wooden stick with wet crumbs sticking to it. Cool for 10 minutes in the pan on a wire rack. Remove the bread; cool on a wire rack.Place the bittersweet chocolate in a microwave-safe bowl; reheat in the microwave on high power for 30 seconds. Drizzle the bread with chocolate; let it stand until set.