First up, preheat your oven to 170 Celsius degrees (150 Celsius degrees with fan)
Then, grease and line a loaf tin with baking paper and place to one side.
Next, melt your butter, vanilla extract and sugar on the hob on a medium heat, stirring regularly.
While the other ingredients are melting, mash your bananas to a pulp, making sure there are no lumps.
Once everything is melted, take your pan off the heat and mix in the bananas until the mixture is smooth. You might need to use a whisk.
Add your egg, and mix everything together well.
Now sift in your flour, getting as much air into the mixture as possible, and stir in your milk, being careful not to knock the air out by beating too hard.
Once the mixture is smooth, pour into your prepared tin and sprinkle with a little Demerara sugar if you have it. This will give your cake a lovely crunchy topping.
Finally, bake in your preheated oven for around 35 minutes, or until a skewer comes clean. If you’re using a fan oven, this might be slightly earlier.
