2. Into your stand mixer place the butter and sugar. Cream together until fluffy (should only take 1-2 minutes). Add the eggs and beat for an additional minute. Add the mashed banana and vanilla and mix until combined.
3. Into a separate bowl combine the oats, flour, salt, baking powder, baking soda and cinnamon. Add to the creamed mixture and mix just until combined.
4. Fold in the chocolate chips.
5. Spray a 9x9 pan with cooking spray and spread the batter out evenly into it.
6. To make the (heavenly and crumbly!) topping, place all ingredients (but the chocolate chips) into a medium sized mixing bowl and stir to combine. Fold in the chocolate chips and sprinkle it all over the top of the cake batter.
7. Bake for 40 minutes, or until a tooth pick inserted into the center comes out clean.