Preheat oven to 350°F. Line a standard 12-cup muffin pan with paper liners.

Whisk together flour, baking powder, baking soda and salt in medium bowl.

Place mashed bananas in a large mixing bowl (or if you want to mash the bananas right in the bowl with a fork, weight out 360g of banana flesh so that you have the right amount). Add both sugars and whisk until glossy and syrupy. Whisk in eggs, cooled melted butter and vanilla until blended. Add dry ingredients all at once and fold them in until just combined.

For the swirl, combine chopped chocolate and cream in a small bowl and microwave until cream is hot. Stir until smooth and chocolate is melted. Add ¼ cup of banana bread batter and stir vigorously until it is smooth and thick. It might look oily and separate at first but continue to stir until it tightens up.

Divide batter evenly among muffin cups. Spoon about 1 teaspoon of fudge mixture into the center of each and then swirl it through with the blunt side of a knife, lifting batter up and around to tuck the fudge swirl in. Tuck a few large chunks of chocolate on top if desired and bake for 18-20 minutes. Transfer to a wire rack to cool, and they are incredibly delicious while warm!