This coffee cake is moist and tender, with a subtle banana flavor. My family loves the oatmeal streusel topping. If you like nuts in your topping, stir in a cup of chopped, toasted pecans or walnuts after cutting the butter into the dry ingredients. It's delicious while still warm, but the banana flavor intensifies if allowed to cool several hours. Also, for a different variation, I sometimes add a cup of chopped, toasted pecans or walnuts to the batter and frost with cream cheese frosting in place of the streusel.
For the topping, combine all ingredients in a food processor and pulse into small moist crumbs (or cut butter into dry ingredients with a pastry blender or even with your fingers). Refrigerate while preparing cake batter.
Preheat oven to 350 degrees. Grease a 9 x 13 baking pan and set aside.
In a large mixing bowl, beat the cream cheese, butter, and sugar until blended. Add eggs, one at a time, beating well after each addition.
Add the bananas and vanilla extract.
Combine the flour, baking powder, baking soda, and cinnamon; gradually add to the creamed mixture.
Pour the batter into the prepared pan, spreading evenly and smoothing top.
Evenly sprinkle the topping onto the batter.
Bake for 25 to 35 minutes, until a toothpick inserted into the center comes out clean. It took 33 minutes in my oven. Cool on a wire rack for at least an hour before cutting. Enjoy!!!