Preheat oven to 375 degrees F (190 degrees C). Lightly grease 12 muffin cups, or line with muffin papers.

In a large bowl, mix together 1 ½ cups flour, baking soda, baking powder and salt. In another bowl, beat together bananas, sugar, egg and melted butter. Stir the banana mixture into the flour mixture just until moistened. Spoon one half of the batter into prepared muffin cups.

Combine the cream cheese, sugar, flour, egg and vanilla and mix well. Pour a tablespoonful onto the batter in the muffin cups. Top the cream cheese with the remaining muffin batter.

In a small bowl, mix together brown sugar, 4 tablespoons flour, oatmeal, cinnamon and butter with a fork until mixture forms coarse crumbs. Sprinkle topping over muffins. I like to use a small ice cream scoop to pile the crumbs on top.

Bake in preheated oven for 18 to 20 minutes, until a toothpick inserted into center of a muffin comes out clean. (When I remove muffins from the oven, if the muffin is spilling over the top of the pan, I take a table knife and gently but quickly push the muffin tops back into the pan on all sides - this makes for a nice rounded top and prettier, more uniform appearance.)