Pre-heat oven to 375°F. Line a muffin tin with paper liners or grease well with butter or oil.
Mix dry ingredients in a bowl and set aside. Melt butter in a saucepan on low heat.
In a large bowl add eggs and beat together. Add milk, melted butter, maple syrup and smashed banana to eggs and mix well. Add dry ingredients to wet ingredients and gently fold in blueberries.
Bake for 25 minutes until the tops spring back when lightly touched.