• Preheat oven to 425° F.

For the Batter

• Whisk the flour, baking powder and salt in a bowl.
• In a separate bowl whisk the egg and sugar until it lightens and becomes a little fluffy.
• Stir in the mashed bananas, buttermilk, butter, vegetable oil and banana extract.
• Add the wet ingredients to the dry and stir. They do not need to be thoroughly combined; some lumpiness is desirable.
• Spray a standard 12-muffin pan with vegetable spray. Fill the muffin pan with the batter. Do not fill to the brim.

For the Streusel

• Mix the ingredients for the streusel topping together with a fork until a crumbly texture is achieved. A little extra flour may be needed.
• Sprinkle one heaping tablespoon of the topping over the top of each muffin.
• Bake for 18 minutes, or until the muffins are done, rotating the pan once. They should be springy to the touch.