Banana bran wholemeal muffins recipe

I absolutely love this recipe and I cannot remember where I first found it. But I have adapted it over the years to suit my taste and diet.

Ingredients:
115grams butter or soya margarine
110grams brown sugar
4 medium sized well ripened bananas mashed
115 ml dairy milk or soya milk
1/2 teaspoon vanilla extract
2 free range eggs
175grams wholemeal flour
120grams wheat bran (I use kelloggs all-bran instead)
1 teaspoon baking powder
1 teaspoon bicarbonate of soda
1/4 teaspoon salt
1/2 teaspoon cinnamon

Instructions:
Preheat the oven to 190 degrees c / 375 degrees f / gas mark 5.
Grease your muffin tin or line with cases.
In a large mixing bowl cream the butter (margarine) and brown sugar until fluffy.
Then add the mashed bananas, milk, vanilla and eggs. Mix well.
Combine the flour, bran, baking powder, baking soda, cinnamon and salt.
Blend into the banana mix.
Spoon the mix into the muffin tray / cases
Bake for 20 to 25 minutes.
Remove from oven, as soon as the muffins are at a tolerable temperature pick one up and knock the bottom with your finger. If it sounds hollow they are cooked. If not return to oven for approximately 2 to 3 minutes. Shouldn't take any longer as they will be dried out by the oven.
Place muffins on a wire rack to cool.