Making banana nut muffins is a straightforward process that even beginners can master. Follow these steps carefully to achieve the best results:

1. Preheat the Oven: Start by preheating your oven to 350°F (175°C). Line a muffin tin with paper liners or grease it lightly to prevent sticking.
2. Prepare the Bananas: In a large mixing bowl, mash the ripe bananas with a fork until smooth. It’s important to use ripe bananas as they are sweeter and impart more flavor to the muffins.
3. Mix Wet Ingredients: Add the melted butter to the mashed bananas and stir well. Incorporate the sugar, beaten egg, and vanilla extract into the mixture. Mix until everything is fully combined.
4. Combine Dry Ingredients: In a separate bowl, whisk together the baking soda, salt, all-purpose flour, and ground cinnamon. Ensure there are no lumps in the dry ingredients.
5. Mix Wet and Dry Ingredients: Gradually add the dry ingredients to the banana mixture. Stir gently until just combined. Be careful not to overmix, as this can lead to dense muffins.
6. Add Walnuts: Fold in the chopped walnuts into the batter, ensuring they are evenly distributed throughout.
7. Fill Muffin Tins: Using a spoon or an ice cream scoop, fill each muffin cup about two-thirds full with the batter.
8. Bake: Place the muffin tin in the preheated oven and bake for 18-20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
9. Cool: Once baked, remove the muffins from the oven and let them cool in the tin for about 5 minutes. Then transfer them to a wire rack to cool completely.