Preheat oven to 400°F. Place muffin liners in the cups of a muffin pan or spray the pan with cooking spray and set it aside.
Mash the bananas and place them in a large mixing bowl. Add in the eggs, beating after each one. Mix in the milk and vanilla extract.
3 ripe bananas, 2 large eggs, ⅓ cup milk, 1 teaspoon vanilla extract
In a separate large bowl, blend together the flour, brown sugar, butter, baking powder, salt, and cinnamon using a pastry blender or the back of a fork.
2 ½ cups all-purpose flour, ¾ cup brown sugar, 6 tablespoons butter, 1 tablespoon baking powder, ¾ teaspoon salt, ¾ teaspoon ground cinnamon
Slowly add in the dry ingredients to the banana mixture. Mix just until everything is mixed together. Do not over mix.
Using a spatula, gently fold in the blueberries.
1 ½ cups fresh blueberries
Fill the lined jumbo muffin cups ¾ full.
In a small bowl, mix together the topping ingredients and sprinkle evenly over each muffin. (Topping is optional.)
½ cup brown sugar, ½ teaspoon ground cinnamon, 1 tablespoon softened butter
Bake for 25 minutes. (15-18 if you use a regular muffin tin.) Let cool slightly before serving.