Preheat oven to 350 degrees F. Coat one 9x5x3-inch loaf pan or two 7x3 1/2x2-inch loaf pans with cooking spray; if desired, line bottom with parchment paper. Set aside. In a large bowl combine flour, cocoa powder, baking soda, and salt. Make a well in the center of the flour mixture; set aside.
In a medium bowl combine eggs, bananas, yogurt, brown sugar, chocolate-hazelnut spread, and oil. Add banana mixture all at once to flour mixture; stir until evenly moistened. Spoon batter into prepared pan(s). Sprinkle top(s) evenly with hazelnuts.
Bake 45 to 50 minutes for the 9x5x3-inch pan or 30 to 35 minutes for the 7x3 1/2x2-inch pans or until a wooden toothpick inserted near the center(s) comes out clean. If necessary to prevent overbrowning, cover loosely with foil for the last 15 minutes of baking. Cool in pan(s) on wire rack(s) 10 minutes. Remove from pan(s); cool completely on wire rack(s). Peel off parchment paper, if using. Wrap in plastic wrap or foil; store overnight before slicing.
Tips: Choose Splenda Brown Sugar Blend as a substitute, if desired. Follow package directions to use product amount equivalent to 1/2 cup brown sugar.
About 3 medium bananas equal 1 cup mashed bananas.
1 1/2 starch, 1 fat