Preheat oven to Fahrenheit 350°

In a medium sized bowl melt butter and milk over low heat

Stir in vanilla and brown sugar until melted

Allow to cool until lightly warmed

Add eggs and whisk to combine

Stir in remaining ingredients except for banana and blueberries

Mash bananas separately and then add to batter

Add blueberries and gently fold for a few strokes

Spoon into well greased muffin tins until ⅔ full

Bake at Fahrenheit 350° for 25 minutes until cupcakes have a domed top and are lightly browned

Serve warm with butter