Preheat the oven to 425 degrees.  Lightly spray a muffin tin with cooking spray.

In a medium bowl, stir together the flour, oatmeal, baking soda, and salt.  Set aside.

In the bowl of a stand mixer, cream together the butter and brown sugar until creamy and fluffy.  

Add the eggs, one at a time, mixing well after each.

Pour in the milk, vanilla extract, banana extract, and mashed bananas.  Thoroughly mix.

Dump in the dry ingredients and mix until just combined.  Do not over mix. You don’t want tough muffins.

Spoon the batter into the prepared muffin cups.

Make the streusel.

In a shallow bowl, using your fingers, mix together the melted butter, flour, powdered sugar, and cinnamon until small crumbs form.

Sprinkle the crumb topping on top of the muffins.  Lightly press them into the batter and top with a bit more crumb topping.

Bake the muffins in the preheated oven for 5 minutes.  Without removing the pans from the oven, reduce the heat to 350 degrees and continue baking for another 20 minutes for jumbo muffins or 13 minutes for standard muffins.  

The muffins are done when a toothpick inserted in the center of a muffin comes out clean and the crumb topping is turning golden around the edges.

Remove the muffins from the oven and cool in the pan set atop a wire rack for 10 minutes.

Use an offset spatula to gently lift the warm muffins from the pan.

Enjoy warm or allow to cool and store in an airtight container.