Preheat oven to 350° and spray a 9”x 5” loaf pan with non-stick cooking spray.
In a large bowl, combine bananas, eggs, sugar, yogurt, oil and vanilla. Gently fold in 2 cups flour, 2 teaspoons cinnamon, baking powder and salt. Stir until just combined, then pour into prepared pan.
In a small bowl, combine ½ cup flour, 1 teaspoon cinnamon, brown sugar and butter. Mix until small crumbles occur. Sprinkle evenly over batter.
Bake 60-65 minutes, until a toothpick inserted in the center comes out clean. Allow to cool in pan 10 minutes, then remove to a cooling rack and serve. Store leftovers in an airtight container up to five days.