Preheat the oven to 200 °C. Spray a 12-cup muffin tin with oil spray or line it with 12 muffin cases.
Dry ingredients
In a stand mixer or large mixing bowl, combine 2 cups flour, 1 tsp baking powder, ½ tsp baking soda, ½ tsp sea saltand ½ tsp cinnamon.
Wet ingredients
Mash 2 ripe bananas in a small bowl. In a separate large bowl, beat ⅓ cup olive oil and ½ cup maple syrup. Add eggs one at a time, beating until light and fluffy. Add the mashed banana, ½ cup Greek yoghurt and 2 tsp vanilla extract and gently stir until just combined.
Make batter
Pour the wet ingredients into the bowl with the dry ingredients and mix until just combined (a few lumps are ok). Gently fold 70 g chocolate chips into the batter and stir to combine.
Bake muffins
Spoon the batter evenly between the 12 muffin cups. Bake the muffins for 18-22 minutes, or until the muffins are golden on top and a toothpick inserted into a muffin comes out clean.
Cool muffins
Place the muffin tin on a wire rack to cool. You might need to run a knife along the outer edge of the muffins to loosen them from the pan if not using muffin cases.
Notes
If you have leftover muffins, store them, covered, in the refrigerator for up to 5 days. Freeze leftover muffins for up to 3 months.