In a large bowl, mash bananas.

Beat in olive oil, eggs, and vanilla, followed by sugar.

Using a sieve over the bowl, sift in the flour and cocoa powder. Add baking soda, and salt and stir all until well combined.

Spoon batter into well greased (or parchment lined) muffin tins. Add one square of bakers chocolate to each muffin, tucking it into the centre of the muffin, leaving a quarter or so of the square above the batter line.

Bake at 400 degrees for 15-20 minutes, until the muffins are firm and your kitchen smells like a chocolate factory.

Sprinkle a tiny pinch of kosher salt over the tops of the muffins, while the chocolate is still hot and melty.