Preheat your oven to 355 °F.
Grease 8 cups of a muffin pan with cookingspray.
In a medium-sized bowl, sift together the flour, baking powder, baking soda andsalt.
In a large bowl, add the sugar and butter and whisk until fluffyandpale.
Add the mashed bananas, egg and vanillaextract and beat until well combined.
Add the flour mixture and mix until just combined.
Gently fold in the strawberry pieces.
Place the mixture into prepared muffincups evenly.
Top each muffin with crumb topping and gentlypress down.
Bake for about 18-20 minutes.
Remove the muffin pan from oven and placeonto a wire rack to cool for about 10 minutes.
Then invert the muffins onto the wire rack tocool before serving.