Heat the oven to 350°F (177°C) and lightly grease a 10-ounce ramekin. In a small bowl, combine flour, baking soda, cinnamon, and salt together. Set aside.
Mash the banana with a fork and add to a medium-sized bowl. Add the sugar and with an electric mixer or a wire whisk whip the banana and sugar together.
Add the melted butter, the egg yolk, and the vanilla; mix well.
Add the dry ingredients and mix until combined.
Pour into the ramekin and bake for 25-30 minutes until golden brown.
Remove from the oven and cool slightly before eating.
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Notes
Expert Tip
Use ripe bananas. Ripe bananas make the sweetest banana bread. When bananas have plenty of brown spots on the skin, they're perfect to use. The browner the skins, the sweeter the banana bread.
Buy bananas and freeze them. It's a great idea to keep overripe bananas handy in your freezer ready for baking. If you've got a few forgotten bananas on your counter, freeze them, unpeeled. Freezing bananas will turn the skin black, but once peeled the flesh will be perfect for making banana bread or banana muffins.
Leave the batter lumpy. When mashing the banana, leave some of the banana chunks. Overmixing the batter can also result in a tough bread.