Preheat the oven to 350F. Line a loaf pan with parchment paper and set aside.

In a small bowl, mix together the crumble ingredients until the crumb holds together when pinched and resembles wet sand. Set aside.

In another small bowl, mix together the cinnamon-sugar swirl.

Whisk together the dry ingredients in a medium bowl.

Add the eggs, oil, maple syrup, applesauce, and vanilla to a large bowl and beat on medium speed with a hand mixer or stand mixer until combined. Add the mashed bananas and mix until just combined.

Add the flour mixture to the wet ingredients and mix on low until combined.

Pour half of the banana bread batter into the lined loaf pan then sprinkle half of the cinnamon-sugar over the batter. Repeat with remaining batter and sugar mixture. Use a knife or chopstick to gently swirl the cinnamon-sugar evenly into the batter.

Crumble the cinnamon streusel evenly over the top of the batter, pressing down gently so it sticks to the loaf.

Bake in the preheated oven for 50-55 minutes or until the top of the banana bread coffee cake is golden brown and a toothpick comes out with a few crumbs on it.

Let the banana crumble bread cool in the pan for 10-20 minutes before removing to a wire rack to finish cooling.

I find that the longer you can wait to slice into it (even overnight), the better it tastes. This lets the flavors really develop.