Preheat your oven to 350°F (175°C) and grease a 9x5-inch loaf pan.

In a medium bowl, whisk together flour, baking soda, salt, and ground cinnamon.

In a large bowl, mash bananas, then add granulated sugar, brown sugar, eggs, oil, and vanilla extract. Mix until smooth.

Gradually stir in the dry ingredient mixture until just combined, then fold in the blueberries.

In a small bowl, mix brown sugar and cinnamon for the swirl mixture.

Pour half the batter into the pan, sprinkle with half the swirl mixture, add remaining batter, then top with the rest of the swirl mixture. Swirl gently.

Bake for 55-65 minutes until a toothpick comes out clean. Tent with foil if browning too quickly.

Cool in the pan for 10 minutes before transferring to a wire rack to cool completely.