Preheat oven to 350°F. Line a 9x5-inch loaf pan with parchment paper, leaving about 1-inch overhang along the sides.
Combine flour, cocoa powder, baking powder, baking soda and salt in a medium bowl and whisk to blend evenly. Sift it if your cocoa powder is very lumpy.
Place mashed bananas in a large mixing bowl (or you can mash the bananas right in the bowl with a fork – you will need 240g of banana flesh which is about 2 medium bananas). Stir in brown sugar. Add yogurt and whisk until combined. Whisk in eggs one at a time until smooth. Mix in oil. Mix in warm melted chocolate. Add dry ingredients and chocolate chips all at once and fold together gently with a spatula until just combined. Do not over-mix. A few small lumps are just fine.
Bake for 45-50 minutes until dark brown on the surface and firm to the touch. A skewer inserted into the center should come out clean. Transfer pan to a wire rack and let cool for 15 minutes, then turn the loaf out of the pan to cool completely on the rack.
For the ganache topping, place chopped dark chocolate in a heatproof bowl. Combine cream, butter, honey and salt in a saucepan over medium-low heat until it just starts to simmer. Remove from heat and pour it over the chopped chocolate. Let stand for 2 minutes, then stir from the center until smooth and silky.
Let the ganache stand for about 40 minutes until thick and spreadable, or refrigerate for about 20 minutes. Spread over cooled banana bread and enjoy!