2 cups (500 g) very ripe bananas, coarsely crushed (2 to 3 bananas) (see note)
1 cup (210 g) sugar
3 1/2 tsp baking soda
1 pinch salt
1/4 cup (60 ml) vegetable oil
1 1/2 cups (225 g) unbleached all-purpose flour
1/2 cup (125 ml) buttermilk
With the rack in the middle position, preheat the oven to 275°F (135°C). Butter and flour a 9 x 5-inch (23 x 13 cm), 7-cup (1.8 litre) loaf pan.
In a food processor or blender, purée the bananas with the sugar, baking soda and salt until smooth.
Transfer the purée into a bowl. Whisk in the eggs one at a time. Add the oil. Add the flour alternating with the buttermilk. Pour the batter into the prepared pan. There should be at least ½ inch (1.5 cm) of free space between the batter and the top of the pan (see note). Place the pan on a baking sheet.
Bake for 2 hours 30 minutes. Let cool completely, for at least 8 hours. Run a thin blade between the sides of the pan and the bread to unmould. To make the bread even more moist, place it in a resealable bag and let sit for a few hours.