Preheat the oven to 350°F / 175°C. Grease a 9 × 5in / 23 × 13cm loaf pan.
Whisk 1¼ cups of all-purpose flour, ½ cup of natural unsweetened cocoa powder, 1 teaspoon of baking soda, and ½ teaspoon of salt.
In another bowl, beat ½ cup of softened unsalted butter and ¾ cup of granulated sugar until creamy. Beat in 2 large eggs, then ¼ cup of plain yogurt, 1½ cups of mashed bananas, and 1 teaspoon of vanilla extract.
On low speed, mix in the flour mixture and 2 tablespoons of hot water just until combined. Fold in ¾ cup of semisweet chocolate chips.
Spread in the pan and sprinkle 2 tablespoons of semisweet chocolate chips down the center. Bake for 60-65 minutes, tenting loosely with aluminum foil halfway, until a toothpick inserted into the center comes out clean.
Cool in the pan on a wire rack for 1-2 hours before slicing.
