Banana tahini chocolate cake

I got on a bit of a roll with tahini baking after making these - couldn't believe I hadn't done more of it before! This was the next thing I tried - was also delicious, although I wished I could taste the tahini...

2 large ripe or overripe bananas (approx 250 g weighed with skins on / ¾ cup mashed)
60 ml veg oil
50 g tahini
1 large egg (at room temp)
50 g caster sugar
35 g soft dark brown sugar
1 tsp vanilla essence
60 g flour
25 g cocoa
¼ tsp fine sea salt
½ tsp bicarbonate of soda
100 g dark chocolate chips
1-2 tsp sesame seeds (to sprinkle on top)

Heat the oven to 170C / 150C Fan / 325F. Grease and line a 1 lb / 450 g loaf tin (approx 21 x 10 x 6 cm / 8.5 x 4 x 2.5 in). Peel and mash the bananas in a large bowl, then beat in the tahini, followed by the oil, then the egg, and finally the sugars and vanilla. Mix flour, cocoa, bicarb and salt together with a fork in a separate, medium bowl, and then slowly beat into the batter. Fold in the chocolate chips. Add the batter to the prepared tin, smoothing the top, and sprinkle over the sesame seeds.

Bake for 45-50 min until risen and firm to the touch, and a skewer comes out almost clean (bearing in mind chocolate). It will probably crack on top. Let cool completely in its tin on a wire rack. Once cold, remove from tin and wrap in parchment then foil and leave it for a day before slicing and eating.