Preheat the oven to 350˚F and line a 9 by 5-inch loaf pan with parchment paper, leaving excess on the two longer sides so you can easily remove the banana bread once baked.

To a large bowl, add bananas, brown sugar, and melted butter. Using a potato masher or fork, mash the bananas until almost completely smooth.

Add Greek yogurt, eggs, and vanilla and whisk until smooth. Add flour, baking soda, cinnamon, and salt and fold with a rubber spatula until no streaks of flour remain. In a separate medium bowl, combine the cinnamon swirl ingredients.

Scrape half of the batter into the prepared pan and top with the cinnamon swirl mixture. Add remaining batter on top, then use a butter knife or cake tester to swirl the batter, creating a marble effect. After swirling the batter, smooth the top of the loaf into an even surface. Bake for 55 to 60 minutes, or until a cake tester inserted in the center of the loaf comes out clean.

Let cool for at least 20 minutes, then remove from pan and cool completely on a wire rack.

While the cake cools, make the glaze. Sift the powdered sugar, cinnamon, and salt into a small mixing bowl. Add the milk or cream and vanilla and whisk until smooth. The consistency should be similar to corn syrup or a runny honey.

Once the cake is cool, remove from the pan and place on a plate or cutting board. Drizzle with glaze and let sit for about 15 minutes before slicing.