Preheat your oven to 200C/400F and line a 12-hole muffin tin with muffin cases.
Add the sugar and egg to a large bowl and mix using a fork or balloon whisk. Add in the oil and vanilla extract, stir, and then add in the yogurt and stir to combine. Next add in the flour and baking soda and mix together using a wooden spoon. Gently fold in all but two tbsp of the chocolate chips and all of the banana chunks.
Fill the muffin cases with the with the cake mixture. Top each with one or two banana chips. Sprinkle on the reserved chocolate chips.
Place the muffins in the oven and cook at 200C/400F for 5 minutes, then turn the oven down to 180C/360F and cook for a further 15-16 minutes until golden. Once cooked, leave to cool in the tin for 10 minutes before removing and cooling further on a cooling rack.