Preheat oven to 175 degrees Celsius (350 degrees Fahrenheit). Line cupcake mould with liners. Set aside.
In a large mixing bowl, whisk buttermilk, melted butter (or oil), sugars, egg and vanilla together until well-mixed. Whisk in the mashed bananas.
Sift in the flour, baking soda and salt into the batter. Fold in the flour mixture with a spatula until no streak of flour remains. (If you have extra banana chunks, stir them in at this point.)
Full the liners with the batter until 3/4 full (usually about 1/4-cup full). Top with slices of bananas and bake for 17 to 20 minutes until a skewer inserted into the centre of the muffin comes out clean and the top of muffin springs back when lightly touched.
Remove the muffin tin and set on a wire rack to cool completely. Store the muffins in an air-tight container overnight before serving.
NOTES
- If no buttermilk is available, replace the buttermilk (3 tablespoons) with milk (3 tablespoons) and add in 1 teaspoon white vinegar or lemon juice and proceed as per recipe.- Adapted from Sally's Baking Addiction